Matthew Haydon v R [2026] EWCA Crim 12

[2026] EWCA Crim 12Case No 202401840 B3
IN THE COURT OF APPEAL (CRIMINAL DIVISION)
ON APPEAL FROM THE CENTRAL CRIMINAL COURT
MR JUSTICE JOHNSON
T20237277
Venue Royal Courts of Justice, Strand, London, WC2A 2LLDate 21/01/2026
Before
PRESIDENT OF THE KING'S BENCH DIVISIONMRS JUSTICE MCGOWANMR JUSTICE HILLIARD
Between
MATTHEW HAYDONAppellantREXRespondent
Mr Adam King (instructed by Reeds, Solicitors) for AppellantMs Margia Mostafa (instructed by CPS Appeals and Review Unit) for RespondentHearing Hearing dates :  22 October 2025
Revised Approved JudgmentThis judgment was handed down remotely at 10.00am on 21 January 2026 by circulation to the parties or their representatives by e-mail and by release to the National Archives..............................WARNING: reporting restrictions may apply to the contents transcribed in this document, particularly if the case concerned a sexual offence or involved a child. Reporting restrictions prohibit the publication of the applicable information to the public or any section of the public, in writing, in a broadcast or by means of the internet, including social media. Anyone who receives a copy of this transcript is responsible in law for making sure that applicable restrictions are not breached. A person who breaches a reporting restriction is liable to a fine and/or imprisonment. For guidance on whether reporting restrictions apply, and to what information, ask at the court office or take legal advice.Dame Victoria Sharp, P.:

Introduction

[1]The appellant, Matthew Haydon was charged on an indictment containing one count of an offence contrary to section 2 of the Explosive Substances Act 1883 (the 1883 Act). That section provides that:
“A person who …unlawfully and maliciously causes by any explosive substance an explosion of a nature likely to endanger life or to cause serious injury to property shall, whether any injury to person or property has been actually caused or not, be guilty of an offence and on conviction on indictment shall be liable to imprisonment for life.”
[2]He was convicted following a 10-day trial at the Central Criminal Court before Mr Justice Johnson and a jury and sentenced to an extended determinate sentence of 8 years and 6 months, comprising a custodial term of 4 years 6 months with an extension period of 4 years.[3]He appeals against conviction with the leave of the single judge on three grounds. Ground 1 is that the judge misdirected the jury on the meaning of likely in section 2. Ground 2 is that the judge was wrong to refuse a defence application to exclude certain evidence on the ground that the prejudicial effect of that evidence outweighed its probative value. Ground 3 is that the judge misdirected the jury on the mental element of the section 2 offence: the argument for the appellant in short is that the mental element of the offence is not foresight of any explosion, but foresight of the nature of (i.e. the extent or size of) the explosion.[4]For the reasons that follow we dismiss the appeal.

Background

[5]Most of the material background was not contentious, or was put before the jury in the form of agreed facts. It can be summarised as follows.[6]The appellant lived with his mother in Bedfordshire in what had been the Haydon family home for 45 years. The appellant had an interest in chemicals and explosives. On the first floor, there were the bedrooms, including a room that the appellant used for storing chemicals and conducting experiments and had turned into a makeshift laboratory.[7]The appellant conducted experiments both in his home and outside which had been observed by his neighbours. He suffers from Attention Deficit Hyperactivity Disorder (ADHD) which manifests itself in an obsessive fixation which at the time was his interest in explosives.[8]On 10 April 2023, the appellant’s mother, Mrs. Haydon returned home at about 4.15pm. At about 5.45pm she heard a loud bang from the room housing the chemicals followed by the appellant shouting “Help me help me”. Mrs. Haydon ran upstairs and opened the door. As soon as she entered there was ‘powdery’ smoke. The appellant was lying on the floor shouting “Help me” and he was bleeding. The blast had smashed the double glazed windows and there was broken glass on the table where the appellant conducted his experiments. Mrs. Haydon made a 999 call for an ambulance. She explained to the operator that the appellant had been “playing around” with chemicals, there had been a big explosion and he had significant injuries, including mangled hands and to his chest.[9]The Haydons’ house was semi detached. The blast was heard by neighbours as a thudding boom, and the wall adjoining the Haydons’ house shook.[10]The appellant was seen by doctors in Accident and Emergency in Bedford Hospital and then transferred to Addenbrookes Hospital. He had suffered serious injuries: blast injuries to his hands and chest and multiple fractures to both hands requiring partial amputation of some of his fingers. The burn pattern on his chest showed a knife case the appellant wore around his neck. The appellant told his mother that he had used acetone and hydrogen peroxide to cause an explosion.A police officeroverhead the appellant saying to a nurse: “it was acetone and hydrogen peroxide but it just makes water when they are mixed so it will be alright”.[11]A fire service team attended the appellant’s house and conducted an initial search. Thereafter police officers attended: they saw blood trailing from the bedroom, gas masks, chemicals and laboratory equipment. The house was cordoned off and adjoining houses were evacuated so they could establish the risks of further explosions and ensure there would be no more.[12]The police were supported by the Explosive Ordnance Disposal and Search Squadron (EOD) from the Ministry of Defence. The EOD search team identified what it assessed as explosive substances above trace level., which were subsequently confirmed and neutralised at the scene.[13]Once EOD deemed the house safe, a police search was conducted. Within the bedroom, the police discovered a number of different chemicals in various locations around the room and a switch with a wire. The chemicals, laboratory equipment, various electronic devices, and handwritten notes were seized by the police. Photographs of the scene after the blast, even allowing for the effect of the blast that had occurred, showed a chaotic scene of jumbled papers, chemicals, dishes, electronic devices and other paraphernalia associated with the appellant’s activities.[14]A rapid review interrogation conducted of the appellant’s laptop uncovered files downloaded on his computer between 7 December 2022 and 1 April 2023. These appeared to be guides or instructions for explosives. The following file names were noted:• The Complete Book of ExplosivesNitrogen TriiodideMakeshift Arsenal by LoweryIntensive High Performance Replacements for RDX Explosives• Kitchen Improvised... Complete Plastic IED 4 DummiesIED 4 DummiesHg-CNO-3• Peroxide-ExplosivesExplosive compoundsMethod of Making Nitrogen Triiodide TNP Synthese 23Nitro Cellulose[15]A more detailed interrogation of the laptop revealed that the appellant had been conducting the following web searches: “Kitchen Improvised Explosives”, “Explosives – The Crown Prosecution Service”, “Man’s ‘experiments’ with explosives were lawful, court rules” and “How to synthesis Hexamethylene triperoxide diamine (HMTD)”.[16]The appellant had sent a message to a contact saved as “Stotty”. The message was sent on 4 April 2023 and read:
“Well holy shitballz my life just flashed in front of me!!! I was making a liquid expl & still developing best practice etc and put a wee tad too much sulphuric acid in to fast and it erupted to the ceiling in flames!!! Thanfully it didn’t kick acid all over and cant believe no burn marks or fukall!!!! Sum1 upder is looking after me man I swear!!!”
[17]Police investigations revealed that the appellant had purchased various chemicals online, including potassium permanganate and aluminium powder on 9 January 2023, ignitable fuses in February 2023, 20 litres of sodium hypochlorite on 17 March 2023, and acetone throughout February and March 2023.[18]The police sent the various chemicals and equipment seized to an expert in chemical analysis and explosive devices. She concluded that the items comprised bulk explosive substances, documentation, chemical precursors and other items that could be used in the manufacture of IEDs (improvised explosive devices).[19]The bulk explosive substances were made safe and disposed of in‐situ once samples were taken. These samples were found to contain triacetone triperoxide (TATP) and HMTD. Chemical analysis indicated mixing of these substances in some samples. TATP and HMTD are sensitive primary high explosive substances. Due to their sensitivity and instability they are not produced commercially apart from as laboratory standards. They are sensitive to flame, friction and impact.[20]Several samples also contained traces indicative of urea hydrogen peroxide (UHP). UHP is found within commercial product ear wax removal and teeth whitening products. It can be made to explode under certain circumstances. However isolation and purification would be required. It can also be used as a source of hydrogen peroxide.[21]One sample contained methyl ethyl ketone peroxide (MEKP) along with dimethylphthalate. This is indicative of a commercial product used in fibre glass hardening. In isolation, MEKP is a sensitive primary high liquid explosive substance which is sensitive to a range of stimuli including flame, friction and impact. Commercial MEKP solutions are not considered an explosive substance.[22]A quantity of viable improvised low explosive was also present. Low explosive substances will burn fiercely when ignited and if suitably confined and ignited they can be made to explode.[23]Damage to the T‐shirt the appellant was wearing and the orange glove he had on his hand was consistent with him being in close proximity to the explosive event. Chemical analysis of samples taken from the T‐shirt indicated that HMTD was part of the explosive charge.[24]Handwritten notes detailing experimentation with explosive substances, including TATP and HMTD and their detonation were present. These notes also highlighted some near misses. The notes included some diagrams of devices, parts of which appeared to have been constructed. Further construction and other materials would be required to produce any viable device.[25]Other chemicals were submitted for analysis and were found to include explosive precursors such as fuels (aluminium powder, iron powder and sulphur) and an oxidiser (potassium perchlorate); dextrin and bentonite are used in the construction of commercial fireworks and pyrotechnic mixtures and could be incorporated into improvised versions.[26]A number of other items contained switches, batteries (an improvised pressure plate and bridge wire) that could be incorporated into other homemade electronics projects such as a doorbell/burglar alarm. Other printed paperwork showed an interest in chemicals and chemistry.[27]The police also seized an Olympus camera with a SD card that had a number of photographs and videos of the appellant conducting various experiments using explosives, for example, 10 grams of TATP being detonated inside a tree stump causing a significant blast.[28]The appellant was arrested on 11 April 2023, and once he was well enough, he was interviewed by the police. The appellant had a solicitor present during the course of the interview as well as an appropriate adult. He gave details of the chemicals he had purchased, how he had experimented with the chemicals and how he had created an explosion.[29]In his interview, the appellant said:
“I caused an explosion. I believe it was unlawful. Um, well, I, I’m not sure- right, I, I caused an explosion. I don’t believe it was malicious. Um, it was, it – it was an accident. It wasn’t an – an intended um...detonation. It was a – a pure accident and – and it resulted from me not cleaning a plate properly…. I have always been intimately um...almost to the point of obsession, uh, obsessed with all kinds of weaponry, explosives in particular. Uh, I think I wrote off to Jim’ll Fix It to ask if I could throw a hand grenade. I wanted to...I, you know in – intrigued me. From a very early age. And um, I uh, I had, I had um – I, since, since, since um – losing my, my daughter and, and, um, I’m talking about …my, my, my, my, my – surviving daughter um, since not having her, her around...I’ve had a lot of time on my hands, yeah. I have combined type ADHD. Amongst other issues, you know, I, I have sort of autistic traits and all sort of co-morbid, overlapping symptoms which basically boils down to the fact that I have an issue with focus, so I, I find it sometimes very difficult, almost impossible to focus on tasks that I’m not interested in. I find it difficult to focus on one thing…. …paradoxically, if I am really interested in something, I hyper focus. And that means that I zone in on that one thing and I forgo everything else, everything else goes out the window, yeah. People talk about looking outside the box. I don’t see a box at all. Yeah. It’s just, you know, so...that – that, that, that’s, that’s, that’s hopefully set a little bit of context. I, um...I, I, I was um, basically researching um...about explosives. Um, and, and I’d, I’d been learning about um, cos the, what happened at the Ariana Grande concert, quite badly affected how, how I felt. It, it upset me yeah… So, when you synthesise this stuff, yeah, obviously it, it, it is comprised of three liquids. So hydrochloric acid is a liquid- they’re all liquids, yeah. When you mix them together in a certain way, um...it isn’t – it generates an exothermic reaction which mean that it produces heat, okay. Now, there are ways of mit- of, of, of controlling that, yeah, obviously. You know can use your imagination, you know, ice. You know we’ve got freezers and stuff like that, okay. So, um, essentially you when – when, once you’ve, once you’ve mixed the cake that you’re baking – you know, once you’ve mixed the chemicals, they are – uh, you get a, um, a white precipitate. Which is the pow- the powder I’m talking about. The, the explosive…”

The trial

[30]The prosecution case at trial was that on 10 April 2023 the appellant caused by an IED an explosion of a nature likely to endanger life (including his own) or cause serious damage to property.[31]The prosecution expert evidence came from three experts in explosives, and included the following. The EOD had revealed a quantity of homemade explosives, TATP, HMTD and PETM. TATP is a sensitive high explosive that serves no commercial or military use. It is inherently dangerous, and has to be mitigated using a desensitising material. Even tiny quantities (less than a gram) pose a risk, so it can only be stored in an EOD bunker with a steel door. HMTD has similar properties. Both TATP and HMTD are primary high explosives, sensitive to shock, friction or flame. Because they are high explosives, they do not require a primer to detonate. Any person manufacturing explosive material can be at risk of serious injury even with as little as one gram. For one gram the potential level of harm is serious injury to the person holding the material; for 10 grams the potential level of harm is very serious harm; for 100 grams it is most likely fatal. The explosion in this case was sufficiently powerful to produce a shockwave with a shattering effect (considerable force had been required to cause the double glazed windows to break) and it had all the hallmarks of being caused by a high explosive.[32]The defence raised was one of lack of intention to cause any explosion and a denial that the appellant was reckless as to whether an explosion would be caused. The appellant accepted he mixed chemicals which caused an explosion but denied that the level of explosives used would have been sufficient to endanger life or cause serious injury to property.[33]In his evidence the appellant accepted that he knew that some of his experiments were intrinsically dangerous, but said he would never let off more than 10 grams of high explosives (TATP, which he found to be the safer and more stable of the chemicals, but which he knew was intrinsically dangerous). The appellant said that on 10 April 2023, he had manufactured around 40 grams of TATP and was drying it in a “desiccator” (a bucket with the chemical on a plate inside it). He agreed that drying TATP made it more likely to detonate and he should have been wearing PPE (personal protective equipment). He said he intended to isolate crystals and look at the substance through a microscope. He placed the 40 grams of TATP on a glass plate which he failed to realise contained traces of HMTD from previous use. After poking the TATP, he caused the explosion. He maintained that he had not intended to cause an explosion, nor did he foresee any risks in his actions.[34]The Route to Verdict invited the jury to answer three questions:(1) Are you sure that the defendant caused by any explosive substance an explosion? That was not in dispute;(2) Are you sure that at the time either the defendant intended to cause an explosion or he foresaw the possibility that he would cause an explosion?(3) Are you sure that the explosion was of a nature that was likely to endanger life or cause serious injury to property?

Ground 1

[35]The appellant submits that the judge misdirected the jury on the meaning of the word likely in section 2 of the 1883 Act.[36]The issue first arose on 16 April 2024 after the judge provided draft jury directions to counsel. The judge’s provisional view was that likely did not mean more likely than not, and instead meant something akin to real likelihood in the sense of an event that could well happen as opposed to an event that was more likely than not to happen. In legal argument the following day, the defence argued that likely must mean more likely than not, rather than could well happen. Counsel relied in particular on Re Harris Simons Construction Ltd [1989] 1 WLR 368 where at p370E Hoffman J had said:
“It cannot be a misuse of language to say that something is likely without intending to suggest that the probability of it happening exceeds 0.5, – as in I think that the favourite, Golden Spurs at 5-1, is likely to win the Derby.”
[37]The defence said that Hoffman J’s example was an exception that proved the rule, and that ordinarily one would refer to something as “likely” to happen if the probability exceeded fifty per cent. That, it was submitted, would be the natural meaning of the word “likely” – particularly in the context of a criminal statute, and where Parliament could have specified if it had wanted to do so that it was criminalising recklessly causing an explosion that might endanger or is capable of endangering life.[38]On 18 April 2024, the judge ruled that the word likely in section 2 amounted to a real likelihood, in the sense that an event could well happen as opposed to an event that was more likely than not to happen. The judge explained why he disagreed with the defence submissions:
“I do not accept Mr King’s submission. I consider that the word “likely” is capable, depending on the context of bearing different shades of meaning. In some contexts, it may mean more probable than not or a greater than 50% chance. In others, it may mean that something could well happen. I do not agree that in the natural and ordinary use of language, it always and necessarily bears the meaning of something being more probable than not. The word is inherently more general or vague than that and does not necessarily indicate a precise distinction between a 49% and 51% chance.”
[39]The judge said it was not helpful to closely analyse the use of the word in past authorities, as each of the respective contexts might give rise to a different interpretation. Rather, it was more helpful to examine the particular statutory context in which the word is used. The judge referred to para 17 of the decision of the Court of Appeal of Northern Ireland in R v Marcus [2013] NICA 60 This passage is set out at para 51 below. where the meaning of likely in section 2 of the 1883 Act was considered. It seemed unlikely to the judge that:
“Parliament would have intended (1) that to sanction causing an explosion that is of a nature that is just more likely than not to cause serious damage to property but (2) not to sanction causing an explosion that is of a nature that might well cause a fatality but where the chance of it doing so or of endangering life is just less than 50%.”
[40]Accordingly,

the judge said he would:

“direct the jury on this issue broadly in accordance with the draft route to verdict that I have provided. I have however made one change. In the draft, I had explained the word “likely” in terms of there being a real likelihood. I consider that the language of “could well” explains what I was intending to convey altogether better.”

The judge then directed the jury in the following terms:

“[I]t’s not necessary to prove that the explosion was of a nature that made it more likely than not that life would be endangered or serious injury to property would be caused. It is sufficient if the explosion was of a nature that could well cause danger to life or serious damage to property. That is what “likely” means in this context.”
[42]Mr King for the appellant submits that the judge erred in directing the jury that likely to endanger life should be taken to mean could well endanger life. This meaning sets a lower threshold than more likely than not, and the distinction between the two meanings is significant. He submits that the judge was wrong to say that the authorities were unhelpful. Rather, the case law supports the proposition that the natural and ordinary meaning of likely is a greater than 50 per cent chance. Further, this interpretation should be adopted where likely imposes criminal liability, or some other serious burden on an individual. Mr King acknowledges some of the authorities are unhelpful to his case, but submits that insofar as they seem to give rise to a more flexible or context specific approach they can be distinguished. Further, Marcus is a Northern Ireland case, and not binding on this court, and, in addition, what was said about the meaning of likely, was obiter.[43]Ms Mostafa for the respondent submits that the cases cited by the appellant illustrate that a context and fact specific approach is taken by the court to the meaning of likely having regard to the particular statute in question. The judge’s approach on the law and on the facts was correct. His ruling reflected the most appropriate definition of likely in light of the facts and evidence in the case.

Some authorities

[44]In Re H (Minors)(Sexual Abuse: Standard of Proof) [1996] AC 563 the House of Lords had to consider the meaning of the word likely in section 31 of the Children Act 1989, the relevant part of which provides that a court may make a care or supervision order if it is satisfied that the child concerned is “likely to suffer significant harm” if the order is not made. Lord Nicholls, with whom Lord Goff and Lord Mustill agreed, declined to accept the submission that “likely” meant probable (Lord Browne-Wilkinson and Lord Lloyd dissented in the result, but agreed with Lord Nicholls on this point). At 584G Lord Nicholls said:
“In everyday usage one meaning of the word likely, perhaps its primary meaning, is probable, in the sense of more likely than not. This is not its only meaning. If I am going walking on Kinder Scout and ask whether it is likely to rain, I am using likely in a different sense. I am enquiring whether there is a real risk of rain, a risk that ought not to be ignored. In which sense is likely being used in this subsection?”
[45]Lord Nicholls provided the answer at p585B to F:
“In this context Parliament cannot have been using likely in the sense of more likely than not. If the word likely were given this meaning, it would have the effect of leaving outside the scope of care and supervision orders cases where the court is satisfied there is a real possibility of significant harm to the child in the future but that possibility falls short of being more likely than not. Strictly, if this were the correct reading of the Act, a care or supervision order would not be available even in a case where the risk of significant harm is as likely as not. Nothing would suffice short of proof that the child will probably suffer significant harm. The difficulty with this interpretation of section 31(2) (a) is that it would draw the boundary line at an altogether inapposite point. What is in issue is the prospect, or risk, of the child suffering significant harm. When exposed to this risk a child may need protection just as much when the risk is considered to be less than 50-50 as when the risk is of a higher order. …It is otherwise if there is no real possibility. It is eminently understandable that Parliament should provide that where there is no real possibility of significant harm, parental responsibility should remain solely with the parents. That makes sense as a threshold in the interests of the parents and the child in a way that a higher threshold, based on probability, would not. In my view, therefore, the context shows that in section 31(2) likely is being used in the sense of a real possibility, a possibility that cannot sensibly be ignored having regard to the nature and gravity of the feared harm in the particular case.”
[46]Cream Holdings Ltd and others v Banerjee and another [2004] UKHL 44 concerned the threshold test for the grant of interim relief provided for by section 12(3) of the Human Rights Act 1998. Section 12 applies if the court is considering whether to grant any relief which might affect the exercise of the right to freedom of expression. Subsection (3) provides that:
“No such relief is to be granted so as to restrain publication before trial unless the court is satisfied that the applicant is likely to establish that publication should not be allowed”
. The court considered Parliament must have intended there to be a flexible threshold for the grant or refusal of relief given the implications of making such a decision before the facts were fully known (in cases of breach of confidence for example). At para 12, Lord Nicholls (with whom Lord Woolf, Lord Hoffman, Lord Scott and Baroness Hale agreed) said:
“As with most ordinary English words “likely” has several different shades of meaning. Its meaning depends on the context in which it is being used. Even when read in context, its meaning is not always precise. It is capable of encompassing different degrees of likelihood varying from “more likely than not” to “may well”
. He then said:
“19…Cases may arise where the adverse consequences of disclosure of information would be extremely serious, such as a grave risk of personal injury to a person. It would be extraordinary if in such a case the court were compelled to apply a ‘probability of success’ test …regardless of the possible adverse consequences… 20. These considerations indicate that ‘likely’ in section 12(3) cannot have been intended to mean ‘more likely than not’ in all situations…The intention of Parliament must be taken to be that ‘likely’ should have an extended meaning…”
[47]Lord Nicholls’ observations in In re H were relied on by this court in R v Neil Whitehouse (1999) (Case No.1999/04553) [2000] Crim.L.R.172 (Pill LJ, Rougier and Morison JJ). Counsel were unaware of this authority, but were provided with a transcript of it prior to the hearing at our direction. After the hearing we also invited the parties’ observations on R v Thacker (Edward) [2021] EWCA Crim 97 and R v Connor [2021] NICA 2 and they provided short supplemental submissions on 12 November 2025.[48]The defendant in Whitehouse was convicted of an offence contrary to Article 55 of the Air Navigation (No 2) Order 1995 (SI 1995/1970). Article 55 of the 1995 Regulations provides that:
"A person shall not recklessly or negligently act in a manner likely to endanger an aircraft, or any person therein."
The appellant had refused to switch off his phone during a flight. On appeal he challenged whether the act was likely to endanger an aircraft, on the grounds that the risk of danger materialising was below 50 per cent, and argued likely must mean probable. His appeal against conviction was dismissed. Pill LJ said that the word likely is protean in character in that its meaning may vary with the context. He concluded that:
“While the present context is very different from that under the Children Act, it has in common the disastrous results which may follow if the danger of which there is a risk, materialises. The consequences in the present context may include great loss of life and damage. In this context we construe the word "likely" in the same way as did Lord Nicholls in In re H . That was the way in which the judge construed it in the second of his suggested meanings: "Is there a real risk, a risk that should not be ignored?" There was in this case evidence of a real risk, a risk that ought not be ignored [and the judge’s] direction sufficiently identified the lower threshold which in our view is the appropriate one.”
[49]In Chief Constable of Lancashire v Potter [2003] EWHC 2272 (Admin) at paras 23 to 25, the Divisional Court (Auld LJ, Goldring J) considered the meaning of likely in relation to the making of anti-social behaviour orders under section 1(1) of the Crime and Disorder Act 1998. Such an order could be applied for by a local authority if a person acted in an anti-social manner that caused or was likely to cause harassment, alarm or distress to one or more persons. Such an order had been sought against the respondent arising from her activities as a street prostitute. Auld LJ at para 30, said much depends on the statutory or other context in which that word is used. He went on to say at para 31:
“Clearly, in cases such as that considered by the House of Lords in Re H & Ors, where the context is the prevention of harm to a child, there is a need to give some elasticity of meaning to the word “likely”
. But where, as here, the word is used in the important, but normally less risky context of proceedings against a person to prohibit him from engaging in anti-social conduct, it would be more appropriate to give it the meaning of more probable than not.”[50]In SCA Packaging Ltd v Boyle [2009] UKHL 37, the House of Lords upheld the conclusion of the Northern Ireland Court of Appeal that Parliament intended likely in paragraph 6(1) of the Disability Discrimination Act 1995 Paragraph 6(1) provided that an impairment which would be likely to have a substantial adverse effect on the ability of a person to carry out normal day-to-day activities but for the fact that measures were being taken to treat or correct it, is to be treated as having that effect. to mean could well happen rather than more likely than not. At para 68 Baroness Hale referred to Lord Nicholls’ observations in Cream at para 12; and at para 70 she drew a distinction between predictions from findings of past fact (referring with approval to what had been said by Girvan LJ in the court below):
“The prediction of medical outcomes is something which is frequently difficult. There are many quiescent conditions…which may give rise to serious consequences if the treatment or the drugs are stopped. These serious consequences may not inevitably happen and in any given case it may be impossible to say whether it is more probable than not that this will occur. This being so, it seems highly likely that in the context of para 6(1) …the word “likely” is used in the sense of “could well happen.”
[51]In R v Marcus [2013] NICA 60(Higgins, Girvan and Coghlin LJJ), the appellant appeal’s against conviction of the offence under section 2 was dismissed. The explosive substance was an IED (a nail bomb) thrown through the window of a house, which then exploded in the hall. One of the grounds of appeal was that the trial judge refused to direct there was no case to answer. It was necessary for the court to consider the relevant threshold of likelihood when considering that submission and the sufficiency of the prosecution evidence. Girvan LJ said this at para 17:
“As was pointed out by the House of Lords in Boyle v SCA Packaging Limited [2009] NI 317 the word “likely” has several different shades of meaning. As Lady Hale at 337 points out predictions are different from past findings of fact. It is not a question of weighing the evidence and deciding whom to believe. It is a question of taking a large number of predictive factors into account. Assessing whether something is a risk against which sensible precautions should be taken is an exercise which is carried out all the time. The context of the relevant legislation may compel the conclusion that when the word “likely” is used, it is in the sense “could well happen” rather than it was probable or more likely than not. Section 2 of the 1883 Act criminalises the causing of explosions which have the real capacity to endanger life or cause serious injury to property, that is to say could well cause danger to life or cause serious physical damage to property. In this case there was clear evidence at the close of the Crown case more than sufficient to raise a prima facie case.”
[52]Marcus was followed in R v Christine Connor [2021] NICA 2(Morgan LCJ, McCloskey LJ and Scoffield J), a Diplock case, where the appellant unsuccessfully challenged her conviction for causing an explosion etc. contrary to section 2 of the 1883 Act. The trial judge had found that the appellant was the attacker in an incident in which pipe bombs were thrown at a passing car and explosions on the roadway followed. The appellant argued the trial judge could not be sure at the close of the prosecution case, that it was pipe bombs (rather than fireworks) that had exploded and thus that the appellant had caused an explosion likely to endanger life. At para 53 the court said the judge had correctly espoused the “could well happen” test applied in Marcus. The court went on to say at paras 55 and 56 that the key consideration was the potential of the devices to endanger life, and the could well legal test focused on the potential of these devices, rather than their actual effects:
“There was an abundance of evidence supporting the view that the devices prepared for the purpose of and deployed in the attack on 16 May 2013 were pipe bombs. The “could well” legal test focuses on the potential of these devices, rather than their actual effects. …The undisputed evidence was that pipe bombs are constructed with the aim of showering shrapnel in all directions. We consider that there was ample evidence to support the judge’s finding that the devices were pipe bombs and that, in those circumstances and in light of the other evidence before him, they were likely to endanger life or cause serious injury to property.”
[53]R v Paul Campbell [2022] NICA 42 (Treacy LJ, Maguire LJ and O’Hara J) also cited Marcus with approval. The appellant was convicted of an offence contrary to section 2 of the 1883 Act. He was alleged to have caused an explosion of a device containing between 500 to 700 grams of explosives in an area adjacent to the wall of a police station, which damaged the cladding of the perimeter of the wall, but did not penetrate its inner brick. The court agreed with the trial judge’s assessment that the nature of the explosion could well have caused an endangerment to life given the size of the explosion and its blast wave. The court said at para 54 to 55 that:
“…the fact that the explosion occurred in an unoccupied area of the house and no one could have been injured by the explosion, […] did not prevent a safe conviction for the section 2 offence. The offence is not causing an explosion that endangers or causes serious injury to property although evidence that it did would be clearly sufficient. The offence is causing an explosion of a nature likely to endanger life or cause serious injury to property. This requires an analysis of the nature of the explosion which will include the capacity of the explosion and whether, it “could well” have caused endangerment to life or serious injury to property.”
[54]Finally we should mention R v Thacker (Edward) [2021] EWCA Crim 97 (Lord Burnett CJ, Jay and Whipple JJ). The appellants were convicted under section 1(2)(b) of the Aviation and Maritime Security Act 1990 (the 1990 Act). The offence requires the prosecution to prove that by means of any device, substance, or weapon, the defendant unlawfully and intentionally disrupted the services of an aerodrome in such a way as to endanger, or be likely to endanger, the safe operation of the aerodrome or the safety of persons at the aerodrome. The appellants had locked themselves on to temporary tripods placed around the nosecone of an aircraft, situated in a remote part of the airport, and which had yet to be towed to its stand. The 1990 Act gives domestic effect to two international instruments Article 1 of the Montreal Convention (the Convention for the suppression of unlawful acts against the safety of civil aviation of 23 September 1971, as supplemented by the Montreal Protocol (the Protocol for the suppression of unlawful acts of violence at airports servicing international civil aviation dated 24 February 1988). ; and because of its ambiguous wording, the court held it had to be construed in a uniform manner across contracting states: see paras 55 and 61.[55]Reference was made to what had been said in both Marcus and SCA Packaging , as to the meaning of likely,with the court doubting (but not deciding that) the meaning of likely could alter according to the context. The court also said it saw force in the submission that if it did, proof of a low degree of likelihood can only be justified if the underlying activity is inherently dangerous. It is unnecessary to refer to the decision in detail. These observations by the court were made in the context of the need in that case to apply principles of general concurrence across the international community, and were not necessary for the court’s decision: see paras 78 to 82.

Discussion

[56]Prior to the passage of the 1883 Act, the use of explosives was regulated by the Explosives Act 1875. That Act was concerned with issues of regulation and safety relating to the manufacture, keeping, selling, carrying and importing of gunpowder and other explosive substances, rather than with the use of explosives with criminal intent.[57]The 1883 Act was introduced during the Fenian dynamite campaign, which involved attacks using explosives on military and civilian targets. In summary, it criminalises the causing of an explosion likely to endanger life or property (section 2); attempts to cause explosions or making or keeping explosive with intent to endanger life or property (section 3); making or possession of explosives under suspicious circumstances (section 4) and being an accessory to the commission of any crime under the Act (section 5).[58]Likelihood is, as Baroness Hale pointed out in SCA Packaging a variable concept At para 65:
“Probability denotes a degree of likelihood greater than 50%. Likelihood, on the other hand, is a much more variable concept.”
See also para 68. and in ordinary usage the word likely can have a number of different meanings. The word occurs in many different legislative contexts, and as the cases illustrate, in order to determine the intention of Parliament when using it, the courts apply ordinary principles of statutory construction. The courts consider the purpose of the enactment (i.e. what it is intended to achieve) and the context; and will reject a meaning (more probable than not for example) if it leads to a consequence that Parliament cannot have intended. In considering that issue, the courts have regard to the underlying issue involved, and where appropriate, the nature and the gravity of the harm that might otherwise fall outside of the scope of the enactment in question.[59]Section 2 of the 1883 Act has as its purpose the protection of the public from serious harm, where the harm contemplated is of danger to life or serious harm to property from an explosion caused by an explosive substance. The broader context is the inherent dangerousness and unpredictability of explosive substances, and the potential risk they can pose (to life and property) if used, stored or manufactured, even in small quantities. Hence the extremely strict regulation of such activities: see The Explosive Regulations 2014 (regulations 26 to 29) and the accompanying guidance, which regulate the storage and manufacture of explosives and the control measures that must be taken to ensure safety.[60]The essential point was pithily put in Whitehouse in relation to a statutory provision which is similar in material respects to the one we are considering here. While the present context in this case is very different from that under the Children Act, it has in common the disastrous results which may follow if the danger of which there is a risk, materialises. The consequences in the present context may include great loss of life and damage.[61]In this context Parliament cannot have been using likely in the sense of more likely than not. The effect of this would be to leave outside of scope cases where the jury is satisfied that the explosion caused by the defendant could well endanger life, or seriously injure property, but that possibility falls short of being more likely than not. The same would apply to a case where the risk of endangerment to life is as likely as not. As the judge put it, it is inherently unlikely that Parliament would have intended to sanction an explosion that is (just) more likely than not to cause a fatality or serious damage to property - but not to sanction causing an explosion that might well cause a fatality or cause serious damage to property (even where the chance of it doing so or of endangering life is just less than fifty per cent). Drawing the line at this point would introduce an arbitrary distinction between likelihoods in circumstances where Parliament intended to protect the public against explosions that are of a nature that could well endanger life or cause serious damage to property and would fail to give sufficient weight to the underlying purpose of the Act, its policy intent, the value of human life and property interests.[62]We agree both with the reasoning and the conclusion of the judge on the meaning of likely in section 2. It follows he made no error in his direction to the jury on this issue.

Ground 2

[63]As set out in our summary of the background, after the explosion, experts carried out a safe search of the appellant’s home. Christopher Hester, one of the experts in explosives called at trial, then compiled a report setting out what had been found. Certain items were photographed in situ, and those photographs were included in a bundle of documents for the jury. On behalf of the appellant Mr King objected to the admission of the finding of the items and several of the photographs. Following argument the judge ruled that the evidence was admissible. He found that it was material which demonstrated the extent of the appellant’s knowledge and interest. “The appellant denies that his conduct in causing an explosion by an explosive substance was unlawful or malicious. The report, including the disputed part of the report, concerns items that were found at the appellant’s home relating to his use of explosive substances and includes evidence that on one view is consistent with his knowledge and know-how in respect of the creation of different types of explosion including by way of an IED. Evidence has already been adduced without objection of individual components that could be part of an IED including a switch. The remaining evidence goes further in demonstrating what the appellant was doing, his level of knowledge and know-how and that is, in my judgment, clearly relevant to questions of whether this was an accident, whether it was unlawful and whether it was malicious.” It is this ruling which gives rise to the challenge to admissibility in ground 2.[64]The appellant argues that the judge was in error when he admitted photographs of devices and diagrams. Mr King submits that the material was unfairly prejudicial and should have been excluded under section 78 of the Police and Criminal Evidence Act 1984.[65]The appellant’s case as we have said was that he had not acted unlawfully or maliciously, and had not intended or foreseen the risk of an explosion or its consequences. Mr King submits that he was “a foolish and chaotic amateur” and the explosion was no more than an accident. He conceded before us that the fact that the appellant’s case was that he was a chaotic amateur would allow some of the items to be admitted to rebut that assertion but maintained the argument that some of the items risked causing undue prejudice. We agree with the judge’s assessment of the material and are sure that the judge was correct to reject that argument.[66]As also touched on above, the appellant had been conducting many experiments in his house and in nearby woods. He had sketches for the design of various explosive devices, switches and timers, including explosive devices containing nails, cut up pieces of wire and ball bearings. He had also built more sophisticated devices, such as a pressure plate.[67]There was no evidence that he had any plans to use these devices against any other person. The case against him was not advanced on that basis. That was made clear to the jury in the summing up. This evidence clearly went to the appellant’s level of expertise and not to any proposed plan to injure or kill.[68]The devices did indeed show the breadth of his interest in the subject and his acquired knowledge. Further they showed the extent to which he was prepared to go to carry out experiments. The notes found clearly demonstrated his ability to appreciate that certain chemicals in combination were dangerous. We can find no error in the judge’s approach. We have no doubt that this material was admissible to prove the prosecution's case that the appellant intended to cause an explosion or foresaw that one might be caused.[69]In any event, if the judge had acceded to the submission, the proposition that he was simply a chaotic amateur would have permitted the prosecution to adduce this material under section 101(1)(f) of the Criminal Justice Act 2003to rebut that false impression.

Ground 3

[70]The appellant submits that the judge misdirected the jury as to the mental element which the prosecution had to prove for a section 2 offence. Mr King submitted to the judge that the mental element for the offence went beyond intention or recklessness as to the causing of an explosion and that the prosecution were required to prove that an appellant intended to cause or was reckless as to the causing of an explosion of a particular magnitude; and that it was then for the jury to consider whether the magnitude of the explosion intended or foreseen was objectively likely to endanger life or cause serious injury to property. Thus, he submitted that a appellant must intend or foresee an explosion of a magnitude that was in fact likely to endanger life or cause injury to property.[71]The judge considered a passage in Blackstone’s Criminal Practice (2024) at B12.249 regarding the mental element of a section 2 offence as follows:
“The mens rea is that the act must be done maliciously…It is often said that there is no need for foresight by D of (a) endangerment of life or (b) serious injury to property. The jury assesses the likelihood of either objectively. Without asserting that this proposition is incorrect or overstated, consider G [2003] UKHL 50 and Cunningham [1957] 2 QB 396.”
The same passage appears in the 2025 edition.[72]The judge also referred to R v PaulCampbell (see para 53 above). He said that the Court of Appeal in Northern Ireland held that when considering the nature of the explosion in a section 2 case, the court was considering the criminal act (actus reus), and that the intention of the appellant was irrelevant to that issue. The judge said that this reflected his own view. He could see no basis in the statutory language for requiring the mental element to extend to the magnitude or scale of the explosion. Accordingly, he directed the jury that the prosecution had to prove that the appellant either intended to cause an explosion or foresaw the possibility that there might be an explosion but continued anyway with what he was doing.[73]Mr King has repeated the submissions he made in the court below. He invites us to consider the position of a person who manufactures a small amount of high explosive which he puts into a suitcase and carries with him unlawfully, recklessly dropping it to the ground. Without his knowledge, someone had introduced a great deal more of the explosive substance to the suitcase. As a result, the explosion which occurs is of a magnitude which is likely to endanger life, whereas without the additional quantity it would not be. Mr King submits that it would not be right for someone to be convicted of a section 2 offence in this situation.[74]This hypothetical example is of course a long way away from the facts of this case. In any event however, in our judgment, the mental element of a section 2 offence is confined to an intention to cause an explosion or foresight that an explosion might be caused and continuing to take the risk of it. There is no requirement of foresight of any degree of resulting harm.[75]Thus, it is not necessary to prove that an appellant intended or foresaw an explosion of a degree which was likely to endanger life or cause serious injury to property. That is a separate and objective question for the jury to decide.[76]We have considered the two cases referred to in Blackstone. In G, the House of Lords held that a person was reckless for the purposes of s1(1) of the Criminal Damage Act 1971 if he was aware of a risk and it was in the circumstances known to him, unreasonable to take the risk.[77]In Cunningham, the appellant was charged with unlawfully and maliciously causing a poison to be taken by another person so as thereby to endanger the life of the other person or to inflict grievous bodily harm upon them, contrary to s23(1) of the Offences Against the Person Act 1861. The appellant stole a gas meter and in so doing, he fractured a gas pipe. Coal gas escaped which the victim inhaled. The Court of Appeal held that “malice” required an intent to do the particular kind of harm that was done, or recklessness, i.e., that the accused has foreseen that the particular kind of harm might be done and goes on to take the risk of it. The court said, “it should have been left to the jury to decide whether, even if the appellant did not intend the injury to [V], he foresaw that the removal of the gas meter might cause injury to someone but nevertheless removed it.”[78]We have also considered Mowatt [1968] 1 QB 421 where the Court of Appeal held that for the purposes of an offence contrary to section 20 of the Offences Against the Person Act 1861, unlawfully and maliciously wounding or inflicting grievous bodily harm, “maliciously” imports an awareness that an act may have the consequence of causing some physical harm to another person, but not necessarily a wound or grievous bodily harm.[79]In R v Savage, DPP v Parmenter [1992] 1 AC 699, the House of Lords approved the decision in Mowatt and also held that for an offence of assault occasioning actual bodily harm, contrary to section 47 of the Offences Against the Person Act 1861, the mens rea required was the mens rea for assault. It was not necessary to prove intention or foresight of physical harm. Lord Ackner explained at p752D-E that the reference to “the particular kind of harm” in Cunningham had its origins in the distinction between harm to the person and harm to property. It was not concerned with the degree of harm foreseen.[80]We have also considered Thacker (paras 54 and 55 above) in this context. The Court of Appeal held that for an offence contrary to s1(2)(b) of the Aviation and Maritime Security Act 1990 - unlawfully and intentionally disrupting the services of an aerodrome in such a way as to endanger or be likely to endanger the safe operation of the aerodrome or the safety of persons at the aerodrome - the prosecution had to prove that an accused person intended to disrupt the services of the aerodrome in the knowledge and with the intention that there would be likely endangerment or jeopardy to aircraft safety in some shape or form (para 85).[81]The court had already held that the appellants’ actions had not created disruption of a kind which was likely to endanger the airport’s safe operation or the safety of persons there. That was enough to mean that the appeal had to be allowed but the court nonetheless went on to consider the mental element of a section 1(2)(b) offence.[82]The prosecution had submitted that the offence was made out if disruption was intended, regardless of intent as to the consequences, and that section 1(2)(b) was an endangerment offence akin to section 23 of the Offences Against the Person Act 1861. The trial judge had directed the jury in accordance with those submissions. The Court of Appeal held that he was wrong to have done so.[83]We note that the language of section 1(2)(b) and of section 2 of the 1883 Act is different. Section 1(2)(b) refers only to the intended disruption of an aerodrome in such a way as to endanger or be likely to endanger its safe operation etc. A section 2 offence on the other hand is committed when a person “maliciously” causes an explosion likely to endanger life or cause serious injury to property. We are satisfied in the light of the authorities we have referred to, that the requirement of “malice” means that nothing more needs to be proved for a section 2 offence than an intention to cause an explosion or foresight that an explosion might be caused.[84]It follows that an accused person does not have to intend or foresee that the explosion is of a particular nature or magnitude. And it would not matter for the purposes of section 2 if a resulting explosion was of a greater magnitude than happened to have been intended or foreseen. That seems to us to be entirely consistent with the inherent danger and unpredictability of explosives. If the consequences of unlawfully causing an explosion are of a very much greater degree of magnitude than could have been intended or foreseen, then depending upon the circumstances, that might afford the offender some mitigation but it does not go to guilt or innocence. That we think is the answer to the point behind the hypothetical example posed by Mr King, were anything like it ever to arise in practice. As a matter of principle, the situation he posited is no different from the situation where an appellant charged with an offence contrary to section 20 of the Offences Against the Person Act 1861 inflicts more serious injury than he intended or foresaw because of factors beyond his knowledge or control, for example because of a particular vulnerability of the victim. The requirement for the appellant to have acted “maliciously” is still satisfied.

Outcome

[85]For the reasons given above, this appeal against conviction is dismissed.