Rostrum Leasing 1 DAC v MAE Aircraft Management WLL [2026] EWHC 57 (Comm)

[2026] EWHC 57 (Comm)Case No CL-2024-000683
IN THE HIGH COURT OF JUSTICE
BUSINESS AND PROPERTY COURTS OF ENGLAND AND WALES
LONDON CIRCUIT COMMERCIAL COURT (KBD)
Venue Royal Courts of Justice, Rolls Building, London, EC4A 1NLDate 15 January 2025
Before
Philip Marshall KC
Between
ROSTRUM LEASING 1 DACClaimantMAE AIRCRAFT MANAGEMENT WLLDefendant
JUDGMENT
Thomas Munby KC and James Kane (instructed by Alius Ventures Limited) for ClaimantLuke Wygas (instructed by Gateley UK LLP) for DefendantHearing Hearing date: 27 October 2025
I direct that no official shorthand note shall be taken of this Judgment and that copies of this version as handed down may be treated as authentic.This judgment has been handed down by the judge remotely by circulation to the parties’ representatives by email and release to Bailii. The date for hand-down is deemed to be 15 January 2025.PHILIP MARSHALL KC:Introduction
[1]This is an application by the Claimant, Rostrum Leasing 1 DAC (“Rostrum”) for summary judgment on that part of its claim by which it seeks recovery of US$5,315,735.67 in rent plus interest and costs said to be due under an aircraft lease and for reverse summary judgment dismissing the counterclaim of the Defendant, MAE Aircraft Management WLL (“MAE”).[2]At the time of the hearing there was also an outstanding application by MAE to amend its defence and counterclaim. That application was first made on 22 September 2025 but was then overtaken by a further application, with a revised draft amendment, on 20 October 2025, a few days before the hearing. Although at one stage it appeared that this late application would be contested, at the outset of the hearing the parties were able to agree that the proposed amendments should be permitted in the latest revised form and the application for summary judgment then proceeded by reference to MAE’s amended statement of case.

Background

[3]Rostrum is an aircraft leasing company formed in the Republic of Ireland. MAE is based in Bahrain and operates cargo aircraft.[4]In early 2021, the parties commenced negotiations over the terms of the lease of a Boeing 737-300PCF aircraft (“the Aircraft”), together with two engines, which eventually led to the execution of a letter of intent dated 10 March 2021 (“the LOI”).[5]The LOI set out draft terms which the parties intended to incorporate into a subsequent lease. It provided expressly that, except for certain provisions regarding confidentiality and what was defined as “the Initial Deposit”, it did not create any binding obligations until a mutually acceptable aircraft lease agreement had been executed.[6]Such an agreement was eventually concluded on 18 May 2021 (“the Lease”) whereby the Aircraft was to be leased in return for the payment of “Rent” defined as a combination of a basic rent of US$160,000 per month (with some minor adjustments) plus supplemental amounts called “Utilization Rent” (related to the number of flight hours over a certain hreshold) and “Supplemental Rent” (covering interest on overdue basic rent among other things). Under clause 3.5 the obligation to pay rent was absolute and unconditional and not affected by, among other things, any withholding, set off, counterclaim, recoupment or other right that MAE might have against Rostrum or any defect in airworthiness, condition or fitness for use of the Aircraft.[7]The Lease contained the following provisions for inspection and acceptance:(1) Under section 6, clause 6.1, MAE was obliged to accept the Aircraft “unless it can demonstrate that the aircraft is not in a condition complying with the conditions set forth in Appendix 1D”.(2) Under paragraph 1.3 of Appendix 1D the Aircraft had to be “airworthy, have an FAA 8130-3 certificate of airworthiness”.(3) Under paragraph 2.1 of Appendix 1D, before the Aircraft was delivered, MAE was to perform a technical inspection to verify that it met the delivery conditions set out in that appendix.(4) Under clause 8.4, after that inspection, MAE was to execute a “Technical Acceptance Certificate” (“TAC”) which was to “constitute conclusive proof” that it had fully examined and investigated the Aircraft, and that:
“..(ii) the Aircraft is satisfactory to Lessee and complies in all technical and other respects with the requirements of Section 6.1 and Appendix 1D, (iii) all actions required under Section 6.1 and Appendix 1D have been performed in full to the complete satisfaction of Lessee and (iv) Lessee has unconditionally and irrevocably accepted the Aircraft for lease under this Lease without any reservation whatsoever (other than completion of the items described in Section 8.1 above and the correction of any non compliance with the Delivery Conditions pursuant to the terms of Appendix 1D, Section 2.3 after completion of the Ferry Flight).” (5) The items described in Section 8, clause 8.1 were the execution of a bill of sale in favour of MAE, deregistration from the US Federal Aviation Administration (”
FAA”) registry and delivery by MAE, of a delivery receipt “substantially in the form” of an appendix called “Appendix 6”, following all of which “Delivery” was deemed to have occurred. (6) Under clause 10.4© the TAC constituted a “waiver of the warranty of description [and] any claims [MAE] may have against [Rostrum] based upon the failure of the Aircraft to conform with such description”. (7) Under clause 10.4(d) “delivery by [MAE] to [Rostrum] of the acceptance certificate will be conclusive proof as between each Indemnitee [which included Rostrum] on the one hand and [MAE] on the other hand that [MAE] has examined and investigated the Aircraft, including the Engines and the Aircraft Documents, and that each is in the condition required hereunder and without defect, except as specifically set forth in such Acceptance Certificate, (whether or not discoverable or difficult of discovery at Delivery) and otherwise in every way satisfactory to lessee.”[8]Under clause 1.9, the date on which the TAC was executed was “the Acceptance Date” which was also “the Rent Commencement Date”, the first date on which basic rent became payable, following which it was payable monthly.[9]Following “the Acceptance Date”, under clause 8.7, MAE was to arrange a ferry flight of the Aircraft from the inspection location to the delivery location on a delivery date to be agreed by the parties.[10]Under paragraph 2.3 of Appendix 1D, MAE had a further opportunity to verify the conformity of the Aircraft with “the Delivery Conditions” in the form of a “Post Ferry Flight Inspection”. If that inspection revealed nonconformity, MAE was obliged to provide a “Technical Inspection Notice” (“TIN”) to Rostrum. On receipt of such a notice, Rostrum then had to elect either(a) to remedy the nonconformity at its own cost within 60 days;(b) in case of an engine, provide a substitute engine meeting certain conditions or(c) to take back the Aircraft. Provided the nonconformity did not impair the airworthiness of the Aircraft, however, MAE was still obliged to take delivery but was then entitled to return the Aircraft in the same condition at the end of the lease.[11]If delivery did not take place by “the Outside Delivery Date” (31 May 2021), either party might terminate the Lease by notice in writing, except that MAE was not entitled to terminate the Lease if the delay was caused by its act or omission (clause 8.2). Further, if MAE failed to comply with the conditions in the lease to allow delivery to take place or failed to take delivery when the Aircraft was tendered for delivery, then it would nonetheless be liable to pay rent (clause 8.4).[12]It is common ground that MAE arranged for its agent, AEC Limited, to perform the technical inspection on 23 April 2021. It then signed the TAC on 30 April 2021, before the final Lease was actually executed.[13]On 19 May 2021, a special airworthiness certificate was issued by the FAA (“the FAA Certificate”) permitting the Aircraft to be flown over US territory. The FAA also issued an Export Certificate of Airworthiness (“ECA”) permitting the Aircraft to be exported to Bahrain and certifying that it “is considered airworthy in accordance with a comprehensive and detailed airworthiness code of the United States Government, and is in compliance with those special requirements of the importing country [i.e. Bahrain] filed with the United States Government”.[14]The Aircraft then landed in Bahrain on either 21 May 2021 or 28 May 2021.[15]Deregistration of the Aircraft from the FAA registry and transfer of title could not, however, occur at this time. This was because MAE had not yet obtained an “Air Operator's Certificate” (“AOC”) from the Bahraini authorities and as a result the Aircraft could not be registered in its name in the Bahraini registry. MAE eventually obtained an AOC on 29 September 2021. Following this, Rostrum arranged for the Aircraft to be deregistered from the FAA registry once MAE paid overdue rent. The Aircraft was then registered in Bahrain on 6 October 2021, with legal title to the Aircraft being transferred to MAE as part of the deregistration process.[16]By August 2021, MAE had requested a reduction in rent and then stopped paying rent entirely by March 2022. It never resumed regular payments, although it has paid some amounts in reduction of arrears from time to time.[17]In 2022 and 2023, MAE discussed various alternative arrangements with Rostrum including one under which it would buy the Aircraft. In anticipation of finance being made available to facilitate such a purchase the parties entered an into an agreement to amend the terms of the Lease ("the Amendment Agreement"). The amendments included a reduction in the level of rent, subject to the fulfilment of certain conditions precedent. These conditions included the payment by MAE to Rostrum of a "Final Additional Lease Payment" in the sum of US$160,000 and the payment of an anticipated State Grant of US$1,650,000. MAE paid the sum of US$160,000 but not the State Grant. Rostrum contends that as a result, the conditions for the Amendment Agreement were not satisfied and the amended terms never took effect.[18]Thereafter in May 2024 MAE made proposals to Rostrum about a possible sub-lease of the Aircraft to another party for a term of 60 months. Clause 15.2 of the Lease permitted sub-letting with Rostrum’s prior consent. It is Rostrum’s case that, as the term under the Lease was due to expire in July 2024, such a sub-lease of the Aircraft to a third party required a lease extension. Rostrum was not willing to grant such an extension and would not permit a sub-lease and so the sub-lease proposal went no further.[19]On 26 July 2024, Rostrum served notice of termination of the Lease and required the return of the Aircraft. By this point Rostrum contends it was owed US$5,115,000 in basic rent, which constituted an “Event of Default” under section 23 of the Lease giving it the right to terminate[20]MAE contends that it has redelivered the Aircraft to Rostrum in either 2023 or 2024 or otherwise relinquished control of the Aircraft to Rostrum at a maintenance facility known as Asia Aero Technic in Subang, Malaysia. Rostrum denies that the Aircraft was returned in accordance with the terms of the Lease either on these dates or on the contractually scheduled termination date.

The Issues

[21]MAE contends that the parties’ relationship prior to the execution of the Lease was governed by the LOI and, after execution, was governed by the Lease only in so far as consistent with the LOI.[22]It further contends that either as a matter of construction of the LOI or Lease or as an implied term there were certain conditions precedent to its obligation to take delivery and pay the basic rent, namely(a) there had to be complete and accurate maintenance records and documents;(b) compliance with “Delivery Conditions” in the LOI and Lease;(c) the Aircraft would be airworthy; (c) a boroscope and engine inspection had to have occurred by MAE prior to a check flight;(d) the Aircraft had to be deregistered from the FAA register on arrival in Bahrain; and(e) Rostrum had to receive an original duly executed delivery receipt in the form of Appendix 6 to the Lease.[23]MAE claims that none of these conditions precedent were met and so it does not accept that there was “Delivery” of the Aircraft within the meaning of the terms of the Lease. In particular it claims that there were numerous and serious faults that required repair before the Aircraft could be used and that as a result there was a delay of many months in the registration of the Aircraft in Bahrain. It contends that these faults meant that the Aircraft was not airworthy on delivery so as to satisfy “the Delivery Conditions” under paragraph 2.3 of Appendix 1D to the Lease.[24]MAE also denies that the signing of a TAC in this case gave rise to the consequence that any defects in the Aircraft were waived. It relies on the fact that the TAC was signed before the Lease was entered into. In the alternative it contends that the TAC was expressed to be subject to conditions and in particular a statement that the Aircraft was in accordance with the specifications, terms and conditions for delivery “…except as expressly set forth on Attachment 3 hereto”. It is said that Attachment 3 set out three matters:24.1 Item 1: One of the engines had a major oil leak which made the Aircraft not airworthy and not serviceable;24.2 Item 2: Maintenance requirements had to be cleared for a period as set out in the Lease and these had to be done prior to the delivery and were not; and24.3 Item 3:
“Airworthiness Directives” had not been done and inspected in accordance with the “Delivery Conditions”
. It is alleged that these matters were never complied with and rendered the Aircraft not airworthy. It is said that Rostrum never signed the TAC, and never resolved the issues identified in Attachment 3 of the TAC, whether within 60 days or at all, and therefore did not fulfil the conditions in the TAC.[25]MAE also contends that the TAC cannot constitute a clear and unambiguous representation regarding its acceptance of the Aircraft sufficient to estop it from raising a lack of airworthiness now.[26]In its original statement of case MAE advanced various other defences including duress, misrepresentation and waiver or estoppel which are abandoned by its amendment. It does, however, maintain an allegation that the Amendment Agreement was legally effective and that there was a breach of an implied term to cooperate by Rostrum’s refusal to permit the Aircraft to be sublet by MAE or be sold. There is also an allegation that there was a breach of an implied term that permission to sublet under clause 15 of the Lease was not unreasonably to be refused. Various other points are raised in respect of the quantum of sums claimed by Rostrum.[27]Rostrum disputes each of the matters raised by MAE but in addition contends that MAE is estopped by convention from contending that there was no “Delivery” of the Aircraft and that no “Rent” is due (adopting the definition of these terms in the Lease).

Principles applicable to Summary Judgment

[28]There was broad agreement between the parties as to the correct approach to an application for summary judgment.[29]The court may give summary judgment against a defendant where it considers that it has no real prospect of successfully defending the claim or issue and there is no other compelling reason why the case or issue should be disposed of at trial (see Civil Procedure Rules, rule 24.3).[30]A summary of the principles to be applied in determining a summary judgment application is contained in the judgment of Lewison J. in Easyair Ltd v. Opal Telecom Ltd [2009] EWHC 339 (Ch) at [15]): “i) The court must consider whether the claimant has a “realistic” as opposed to a “fanciful” prospect of success: Swain v Hillman [2001] 2 All ER 91; ii) A “realistic” claim is one that carries some degree of conviction. This means a claim that is more than merely arguable: ED & F Man Liquid Products v Patel [2003] EWCA Civ 472 at [8] iii) In reaching its conclusion the court must not conduct a “mini-trial”: Swain v Hillman iv) This does not mean that the court must take at face value and without analysis everything that a claimant says in his statements before the court. In some cases it may be clear that there is no real substance in factual assertions made, particularly if contradicted by contemporaneous documents: ED & F Man Liquid Products v Patel at [10] v) However, in reaching its conclusion the court must take into account not only the evidence actually placed before it on the application for summaryjudgment, but also the evidence that can reasonably be expected to be available at trial: Royal Brompton Hospital NHS Trust v Hammond (No 5) [2001] EWCA Civ 550; vi) Although a case may turn out at trial not to be really complicated, it does not follow that it should be decided without the fuller investigation into the facts at trial than is possible or permissible on summary judgment. Thus the court should hesitate about making a final decision without a trial, even where there is no obvious conflict of fact at the time of the application, where reasonable grounds exist for believing that a fuller investigation into the facts of the case would add to or alter the evidence available to a trial judge and so affect the outcome of the case: Doncaster Pharmaceuticals Group Ltd v Bolton Pharmaceutical Co 100 Ltd [2007] FSR 63; vii) On the other hand it is not uncommon for an application under Part 24 to give rise to a short point of law or construction and, if the court is satisfied that it has before it all the evidence necessary for the proper determination of the question and that the parties have had an adequate opportunity to address it in argument, it should grasp the nettle and decide it. The reason is quite simple: if the respondent's case is bad in law, he will in truth have no real prospect of succeeding on his claim or successfully defending the claim against him, as the case may be. Similarly, if the applicant's case is bad in law, the sooner that is determined, the better. If it is possible to show by evidence that although material in the form of documents or oral evidence that would put the documents in another light is not currently before the court, such material is likely to exist and can be expected to be available at trial, it would be wrong to give summary judgment because there would be a real, as opposed to a fanciful, prospect of success. However, it is not enough simply to argue that the case should be allowed to go to trial because something may turn up which would have a bearing on the question of construction: ICI Chemicals & Polymers Ltd v TTE Training Ltd [2007] EWCA Civ 725”. claim that is more than merely arguable: ED & F Man Liquid Products v Patel [2003] EWCA Civ 472 at [8] Hillman everything that a claimant says in his statements before the court. In some particularly if contradicted by contemporaneous documents: ED & F Man Liquid Products v Patel at [10] available at trial: Royal Brompton Hospital NHS Trust v Hammond (No 5) follow that it should be decided without the fuller investigation into the facts at trial than is possible or permissible on summary judgment. Thus the court should hesitate about making a final decision without a trial, even where there is no obvious conflict of fact at the time of the application, where reasonable grounds exist for believing that a fuller investigation into the facts of the case outcome of the case: Doncaster Pharmaceuticals Group Ltd v Bolton has before it all the evidence necessary for the proper determination of the question and that the parties have had an adequate opportunity to address it in argument, it should grasp the nettle and decide it. The reason is quite simple: if succeeding on his claim or successfully defending the claim against him, as the determined, the better. If it is possible to show by evidence that although material in the form of documents or oral evidence that would put the documents in another light is not currently before the court, such material is give summary judgment because there would be a real, as opposed to a fanciful, prospect of success. However, it is not enough simply to argue that the case should be allowed to go to trial because something may turn up which

would have a bearing on the question of construction: ICI Chemicals &

[31]Mr Wygas for MAE also drew attention to the Civil Procedure 2025 (“White Book”) commentary at paragraph 24.3.2.4 which refers to observations of Chief Master Marsh in Commerz Real Investmentgesellschaft MBH v TFS Stores Ltd [2021] EWHC 863 (Ch) that there was an overlap between the idea of a point of construction not being "short" and the second limb of CPR r.24.3: there may be some points that the court is capable of grappling with that, nevertheless, due to the context in which they arise or other factors, are best left to be dealt with at a trial. The Application Preliminary Points

The Application

[32]Before considering the principal issues for determination on the application, I address first some preliminary matters that may affect the correct approach to other points that are in contention.[33]The first of these preliminary questions is as to which agreements actually govern relations between the parties. MAE has advanced an argument in its amended statement of case that the LOI was a binding agreement which took precedence over the Lease (since it contends that the Lease only governed the parties’ relations in so far as consistent with the LOI). It also appears to be basing part of its defence and counterclaim upon implied terms of the Amendment Agreement which presupposes that this further agreement had legal effect.[34]As regards the LOI I reject the contention that it had any legal effect beyond its provisions regarding confidentiality and what it referred to as “the Initial Deposit”. The LOI provided expressly that it would not create any binding obligation on either party until a definitive lease came to be executed. When the Lease did come to be executed on 18 May 2021, it provided at clause 27.7, that "any prior or contemporaneous written or oral understandings with regard to [the Aircraft] are superseded hereby in their entirety". In my judgment it is plain that the terms of the obligations between the parties, relevant to the present dispute, are to be found in the Lease not the LOI.[35]As regards the Amendment Agreement the case of MAE is not entirely clear. It accepts that the Amendment Agreement could only take effect if certain conditions were satisfied and admits that not all of them were. It nevertheless appears to allege the breach of an implied term to cooperate and not to prevent performance caused by the refusal of Rostrum to agree to a sublease of the Aircraft. I reject the contention that there could be any implied term requiring Rostrum to agree to a sublease of the Aircraft. Such an implied term would contradict the express terms of the Lease, which give Rostrum the absolute right to refuse consent to any sublease (see clause 15.2). It is well established that no terms can be implied that contradict the express terms of an agreement (see Lewison, The Interpretation of Contracts (8th ed) at [6.109]).[36]I note that MAE advances the further contention that consent to a sublease could not be unreasonably refused. I do not consider such an implied term as either necessary or obvious and do not regard it as appropriate for it to be implied into a detailed and carefully drafted contract of this kind (see Lewison, supra, Section 6). But in any event it would not assist MAE given that (for the reasons set out below) there had already been a default under the Lease by the time the Amendment Agreement had concluded by reason of the failure to pay the basic rent and the existence of a default is an absolute bar to any sublease under the provisions of clause 15.2 of the Lease quite independently of any issue of consent. In its evidence MAE seeks to rely on the absence of any notice of default but under clause 23(a) of the Lease a failure to pay rent when due which continues for three days constitutes a default without the need for any notice. There was such a failure to pay rent here.[37]A further preliminary question arises regarding which conditions precedent applied in respect of the obligation of MAE to take delivery and pay the basic rent. To an extent this is connected with some of the matters addressed above because MAE contends that certain conditions precedent arose from the LOI. I have already concluded that the LOI had no binding effect in any relevant sense. As regards the other suggested conditions precedent that Rostrum had to fulfil, I reject these in so far as they go beyond what was expressly and comprehensively provided for in clause 7.2(b) of the Lease (there being no scope to imply any of the further conditions suggested either as being necessary or obvious). In relation to the Aircraft itself, clause 7.2(b) required that “the Aircraft shall comply with the Delivery Conditions”. The Delivery Conditions are set out at Appendix 1D and are exhaustive since paragraph 1.1 provides that “[u]nless expressly provided in this Appendix 1D, the Aircraft shall be delivered to Lessee in an “as-is, where is” condition” (meaning the lessee takes it “as he finds it without any warranty as to quality or condition” (see The Morning Watch [1991] ECC 103 at [35]) and Hirtenstein v Hill Dickinson LLP [2014] EWHC 2711 (Comm) at [51]). They include a requirement that the Aircraft be airworthy (paragraph 1.3); a requirement that “Aircraft Documents” be provided on the “Acceptance Date” (paragraph 2.2); provision for MAE to complete a “Technical Inspection” of the Aircraft to verify that it met the delivery conditions (paragraph 2.1); and, as set out above, express provision that defects notified pursuant to that Technical Inspection should give Rostrum an election whether to remedy them or terminate the Lease. But all of these provisions were also subject to the provisions in clause 8 of the Lease that compliance would largely have been confirmed prior to delivery by execution of the TAC. I should add in particular that execution of a “Delivery Receipt” was not a condition precedent to the obligation to take delivery. Under clause 8.1 it was an element of the delivery process but it was something that MAE was required to do. Its failure without more to execute such a receipt could not affect delivery since clause 8.4 provided that if MAE “fails to… take delivery of the Aircraft when properly tendered for delivery by Lessor in the condition required under this Lease (including execution and delivery of the Delivery Receipt)”, then it would still be obliged to pay rent.

Delivery and Acceptance

[38]As Mr Wygas for MAE appeared to accept, the central issue is whether there was “Delivery” and “Acceptance” within the meaning of the Lease and whether there was an obligation to pay “Rent” and in particular, “Basic Rent”, as those terms are defined in that agreement.[39]In my judgment, this issue can be resolved by reference to the doctrine of estoppel by convention. Even if MAE were correct in its case regarding the true interpretation of the Lease, the state of the Aircraft and the effect of the TAC, there is still no real prospect of it successfully establishing at trial that “Delivery” did not occur, that there was no “Acceptance” and no “Rent” was payable under the Lease. In circumstances where MAE had in fact paid such “Rent” over many months without reservation it is estopped by convention from so contending.[40]The principles applicable to estoppel by convention were recently reviewed by the Supreme Court in Tinkler v Revenue & Customs Commissioners [2022] AC 886. Lord Burrows, giving the principal judgment, stated at [53] that the principles set out in Revenue & Customs Commissioners v Benchdollar [2009] EWHC 1310 (Ch) subject to one qualification arising from the case of Blindley Heath Investments Ltd. v Bass [2017] Ch.389, were correct. In Blindley Heath (where the estoppel arose for consideration in a contractual context) Hildyard J (sitting in the Court of Appeal) explained the overall position as follows: “73. Estoppel by convention is not founded on a unilateral representation, but rather on mutually manifest conduct by the parties based on a common, but mistaken, assumption of law or fact: its basis is consensual. Its effect is to bind the parties to their shared, even though mistaken, understanding or assumption of the law or facts on which their rights are to be determined (as in the case of estoppel by representation) rather than to provide a cause of action (as in the case of promissory estoppel and proprietary estoppel); and see Snell's Equity , 33rd ed (2015), para 12-012. If and when the common assumption is revealed to be mistaken the parties may nevertheless be estopped from departing from it for the purposes of regulating their rights inter se for so long as it would be unconscionable for the party seeking to repudiate the assumption to be permitted to do so (and see, for example, Norwegian American Cruises A/S (formerly Norwegian American Lines A/S) v Paul Mundy Ltd (The Vistafjord) [1988] 2 Lloyd's Rep 343 , 353 in the judgment of Bingham LJ)…91. Briggs J elaborated on this in Revenue and Customs Comrs v Benchdollar Ltd [2010] 1 All ER 174 when summarising the principles he considered to be applicable to the assertion of an estoppel by convention arising out of non-contractual dealings, which he derived largely from another decision of this court, namely Keen v Holland [1984] 1 WLR 251 . His summary was as follows, at para 52: “(i) It is not enough that the common assumption upon which the estoppel is based is merely understood by the parties in the same way. It must be expressly shared between them. (ii) The expression of the common assumption by the party alleged to be estopped must be such that he may properly be said to have assumed some element of responsibility for it, in the sense of conveying to the other party an understanding that he expected the other party to rely upon it. (iii) The person alleging the estoppel must in fact have relied upon the common assumption, to a sufficient extent, rather than merely upon his own independent view of the matter. (iv) That reliance must have occurred in connection with some subsequent mutual dealing between the parties. (v) Some detriment must thereby have been suffered by the person alleging the estoppel, or benefit thereby have been conferred upon the person alleged to be estopped, sufficient to make it unjust or unconscionable for the latter to assert the true legal (or factual) position.”92. As to (i) above, we do not think there must be expression of accord: agreement to the assumption (rather than merely a coincidence of view, with both proceeding independently on the same false assumption) may be inferred from conduct, or even silence: see per Staughton LJ in Republic of India v India Steamship Co Ltd (No 2) [1998] AC 878 , 891. However, something must be shown to have “crossed the line” sufficient to manifest an assent to the assumption. 93. The question whether the parties manifested assent to the assumption by something said or some conduct which clearly crossed the line is largely a question of fact”.[41]In this case it is evident from the lengthy evidence that MAE has adduced that, on its own case, it fully appreciated that the Aircraft had the alleged defects, which it now relies on as preventing “Delivery” and “Acceptance” within the meaning of the Lease and obviating any obligation to pay “Rent”, before rental payments were actually made. For example, the first witness statement of Mr Abdulrahman Shuwaiter, served on its behalf, at paragraph 40 emphasises the existence of various alleged defects (which he enumerates in the following paragraph) and further emphasises that “the Defendant made numerous complaints to the Claimant at the time regarding the various defects”. Yet at the same time it paid basic rent as provided for in the Lease without any qualification. As to this, the following is in my judgment significant:41.1 Even in the period immediately after a number of defects in the Aircraft were allegedly identified by MAE rent has been paid without qualification. Thus, for example, various emails passing between personnel at MAE, including its former Chief Executive Officer, Paul Hogan, and personnel at Rostrum in the period between 13 July 2021 and 9 September 2021 refer to arrangements for the payment of rent without any reservation or objection. In an email of 26 August 2021 Mr Hogan asked for “a spreadsheet with our payment schedule for the remainder of the lease with the dates so we can plan this for our cash flow”.41.2 MAE has now positively relied on payments of “rent/hire, maintenance reserves” in 2021, 2022 and 2023 in paragraph 8C of its amended defence.41.3 In the evidence filed on behalf of MAE, reliance is placed on the payment of such rent - see, for example, the first witness statement of Mr Shuwaiter, paragraph 15 and that of Dean Anthony Frances, paragraph 38.41.4 The following passage appears at paragraph 43 of the first witness statement of Ms. Bree Taylor, the solicitor for Rostrum:
“I am instructed by Rostrum that no employee or agent of Rostrum has at any time represented to [MAE] that it did not have to pay the Rent. On the contrary, a letter from [MAE] dated 23 October 2024…makes open proposals as to various things including “Payment towards settlement of account – USD 5.3m…Further, after the date of the Claim Form was issued but before these proceedings were served [MAE] did in fact pay USD 400,000 to Rostrum in part payment of the debt for Unpaid Rent”
. The only response to this is contained in the witness statement of Mr Frances at paragraph 52 where he asserts that “this was not accurate” and refers to alleged statements by Rostrum personnel “in or around May/June 2021 onwards to MAE…that MAE did not have to pay for repairs or delays due to Rostrum’s omissions and failures and the condition of the Aircraft in the USA and upon landing in Bahrain”. This appears to be directed to supporting a case of waiver that MAE has now abandoned. It does not address the issue of why rent was actually paid by MAE or as to why it was accepted that US$5.3 million was due in October 2024 or as to why US$400,000 was paid after issue of the proceedings. 41.5 In the Amendment Agreement there was express provision for the payment of US$160,000 in respect of rent, which was again discharged without qualification or reservation (see clause 1.2 and Schedule 1, Part A, paragraph 6(b) and see the email exchanges between the parties on 13 to 15 March 2024 regarding payment and the bank payment confirmation showing a payment to Rostrum on 17 March 2024).[42]In the circumstances, whatever may have been the true position regarding the state of the Aircraft on its arrival with MAE, it is clear that both parties have proceeded on the assumption that basic rent was due and payable under the Lease and that this assumption was expressly shared between them (there being numerous communications that “crossed the line” sufficient to manifest assent to the assumption in the sense used in Blindley Heath). Further, in my judgment, it is plain that MAE assumed some responsibility, in the sense that it conveyed an assumption or understanding that it expected Rostrum to rely upon. If its personnel had not conveyed any such understanding it would have affected the accounting between the parties, the grant of further time for payment that Rostrum permitted in 2021 (as to which see the emails involving Mr Hogan referred to in paragraph 39.1 above) and, most importantly, the continued retention of the Aircraft by MAE. For the same reasons it is plain that Rostrum relied upon the common assumption and not just its own independent view, that this affected the mutual dealings between the parties and that as a result MAE has retained possession of the Aircraft over the whole term of the Lease, such that it would be unconscionable for it now to retreat from the position that it formerly adopted. Had the position been that MAE was not willing to accept that “Delivery” and “Acceptance” had occurred and that rent was payable, then Rostrum would have been in a position to terminate the Lease and obtain the return of the Aircraft (exercising its rights under clause 8.2 of that agreement).[43]MAE has made no submissons in opposition to the case presented by Rostrum based on estoppel by convention. When I raised the issue with Mr Wygas at the start of his submissions he realistically accepted that there was a tension between the payment of rent and the allegation of non-delivery. But in my judgment there is not merely a tension. Having regard to the evidence, the payment of rent in combination with the other circumstances described above mean that there is no real prospect of MAE successfully defeating the case based on estoppel.[44]Although, in light of the above, it may be unnecessary for my decision on the issue of whether there was “Delivery” and “Acceptance” within the meaning of the Lease, I also reject the argument that the TAC is not also sufficient to give rise to a contractual estoppel, applying the approach adopted in by the Court of Appeal in Olympic Airlines v ACG Acquisition XX LLC [2013] EWCA Civ 369. The provisions for an acceptance certificate in that case are very similar to those in the Lease and were held to bar any claim that the aircraft was not in the condition stated. Here the TAC provided an acceptance of the Aircraft which, as in Olympic, is contractually conclusive.[45]It is true that the TAC was actually executed on 30 April 2021 and pre-dated the execution of the Lease but it has clearly been treated by both parties as the TAC for the purposes of the provisions of the Lease (see, for example, the first witness statement of Mr Shuwaiter, paragraphs 41 and 48 to 50).[46]MAE also relies upon the qualification to the TAC and the defects identified in Attachment 3 to that document which it alleges were never rectified. But, as already mentioned, under paragraph 2.3 of the Appendix 1D to the Lease, even if defects were considered sufficiently serious to result in non-compliance with “Delivery Conditions” and to be specified in a TIN, a failure to remedy them would not impact on the requirement that MAE accept delivery and pay rent. It would simply have meant that the Aircraft only had to be returned with the same defects at the end of the term unless they affected airworthiness.[47]In order to address this point MAE alleges that the FAA Certificate showed that the Aircraft was not airworthy. In particular MAE has placed reliance on the fact that the FAA Certificate recorded that the Aircraft would need permits from foreign authorities for transit across the airspace of foreign states because it did “not meet the airworthiness standards of Annex 8 to the Convention on International Civil Aviation” andboth parties provided additional written submissions on the significance of this qualification. In my judgment, however, this is nothing to the point. Appendix 1D equates airworthiness to having an FAA 8130-3 certificate of airworthiness. On MAE’s own evidence (contained in the exhibits to Mr Shuwaiter’s third witness statement) there was an FAA 8130-3 certificate that was reviewed by the Bahraini Civil Aviation Authority with the only query on the document arising from American dating having been adopted. The same certificate was noted in the TAC. Applying the express provisions of the Lease the Aircraft was therefore airworthy.[48]For the above reasons, I would have concluded that “Delivery” and “Acceptance” occurred within the meaning of the Lease by virtue of the terms of the TAC and the lack of any TIN following the ferry flight to Bahrain and that as result rent was payable.

Other matters

[49]There are a number of further points raised by MAE in regard to the claim which I now address.[50]First, it is said by MAE that the basic rent of US$160,000 provided for under the Lease included an element of utilisation rent or maintenance reserves that were not due. The difficulty here is that there is no such provision in the Lease. The Lease simply provides for “Basic Rent” at $160,000 per “Rent Period” and “Utilisation Rent” at $400 per flight hour in excess of 260 flight hours or 130 cycles. There is no reference to maintenance reserves. There is no provision for rent to be refundable if the Aircraft is not used to any anticipated extent or if any alleged maintenance reserves are not used. The allegation that there was a term that any maintenance would be carried out by Rostrum conflicts with clause 12.1 of the Lease, under which MAE was to “cause an Approved Maintenance Organization to, at Lessee’s sole cost and expense, service, repair, overhaul, test and maintain the Aircraft and each Item of Equipment”.[51]Next MAE contends that it deposited the Aircraft at a facility in Malaysia in or before February 2024 and that this constituted return of the Aircraft for the purposes of the Lease and terminated the obligation to pay rent. The provisions governing the return of the aircraft are contained in Section 22 of the Lease. Under clause 22.1 the aircraft was to be returned to MAE’s facility in Bahrain or such other location as was mutually agreed and a “Return Acceptance Certificate”, substantially in the form of Appendix 4, was to be executed. Furthermore, the Aircraft was to be registered in the name of Rostrum (clause 22.5). Under clause 22.3 MAE was also to comply with the requirements of Appendix 1E which included the following:51.1 Prior to return, the parties were to agree on a timetable for Rostrum to perform an inspection at MAE’s cost (see paragraph1.1 of Appendix 1E);51.2 MAE was to provide Rostrum reasonable access to the various documents (including maintenance records) (see paragraph1.2 of Appendix 1E); and51.3 On the date of return, the Aircraft was to be in an airworthy condition (see paragraph 2.2 of Appendix 1E).[52]There is no evidence that any of the above requirements of clause 22 and Appendix 1E were completed prior to February 2024. In particular, there is not even evidence that MAE informed Rostrum that they were returning the Aircraft prior to that date. The second witness statement of Mr Shuwaiter, on behalf of MAE merely states, at paragraph 40, that Rostrum either knew that the Aircraft was at a facility in Malaysia "or they could have checked on the website FlightAware”. The conduct of MAE is also inconsistent with any notification of a return. According to the amended defence, at paragraph 12(a), MAE was still attempting to secure a sub-lease of the Aircraft from April 2024 with discussions continuing "from June 2024 onwards", which sub-lease could only be possible if the Aircraft had not been returned.[53]Given that the Aircraft had not yet been returned, the Lease term continued (see clause 22.4(a)). This meant that MAE remained obliged to insure the Aircraft (see clause 19.1) with the consequence that the allegation at paragraph 29A of the amended defence, that MAE was under no obligation to insure the Aircraft after February 2024 because the Lease had ended, cannot be maintained. It also follows that MAE's obligation to maintain the Aircraft at its sole cost continued (see clause 12.1).[54]The evidence filed on behalf of Rostrum provides details of how the outstanding rent is calculated (in particular in the first witness statement of Ms. Bree Taylor, at paragraphs 20 to 21) although the calculations may need to be updated. In its amended defence MAE has claimed that credit has not been given for the payments it has made. It has, however, provided no explanation of what payments have been missed in Ms. Taylor’s evidence. I therefore reject this defence as also having no real prospect of success. MAE should have been well able to identify any missing items if there were any.[55]On the question of quantum MAE says that the claim for outstanding basic rent should be the subject of set-off in respect of the counterclaim of MAE for damages. In my judgment that contention has no real prospect of success having regard to the express provisions of clause 3.5, which exclude set off.[56]There is, however, more substance to MAE’s case on the question of mitigation of loss. The position, in my judgment, differs as between the period before and after the notice of termination of 26 July 2024. Prior to such notice the Lease continued under clause 22.4(a) and the claim is one for debt rather than damages. In respect of that claim no issue of mitigation would arise. After the notice of termination, however, there is a properly arguable case, with at least a real prospect of success, that basic rent ceased to be claimable and that instead Rostrum was limited to seeking damages for a repudiatory breach that had been accepted. In respect of such claim for damages issues of mitigation would arise which are not capable of being resolved summarily on this application. Further, if for any reason this analysis were wrong and rent could continue to be claimed notwithstanding the notice of termination, there would also be a properly arguable case, with a real prospect of success, that the provisions of clause 22 of the Lease, that permitted rent to continue to be claimed, including at double the original rate in certain circumstances, was unenforceable as a penalty. Issues as to whether the amount provided for was disproportionate to any legitimate interest in recovery and beyond any genuine pre-estimte of loss would potentially need to be addressed (see the discussion in MSC Mediterranean Shipping Co. S.A. v Cottonex Anstalt [2015] EWHC 283 (Comm), at [89] to [116] and FW Aviation Holdings 1 Ltd. v Vietjet Aviation JSC [2025] EWHC 928 (Comm) at [36] to [62]). These matters are not appropriate for summary determination on the materials before me. I note that Rostrum argues that such provisions are not a form of secondary obligation arising on default but a conditional primary obligation and so cannot constitute a penalty (relying on Cavendish Square Holding BV v Makdessi [2015] UKSC 67 at [74]). But in my judgment this requires a proper assessment of what in substance the provisions amount to which is not appropriate for summary determination on this application.[57]For the above reasons, the application for summary judgment in respect of the part of the claim concerning outstanding rent succeeds but only respect of the period up to 26 July 2024. As I understand it, the amount of rent due in respect of that period is US$5,115,000 but credit may need to be given for sums paid since the proceedings commenced. I will hear further submissions on the precise figure if, for any reason, it cannot be agreed having regard to my findings and conclusions set out above.

The counterclaim

[58]I have not found the precise bounds of the amended counterclaim of MAE very easy to identify. Nevertheless doing the best I can by reference to the current statement of case, I regard a claim for damages based on an alleged failure to rectify defects identified in the TAC itself (which MAE claims were never rectified at any time) is one that ought to be resolved at a trial. This means that the relief claimed in the amended counterclaim, paragraph 48 survives to this extent.[59]The claims for declaratory and other relief in paragraphs 44, 46-49(a) and (b), 49A and 49C are ones which have no real prospect of success or are incapable of being maintained for the reasons I have already covered when addressing the claim.[60]Paragraph 49B of the amended counterclaim refers to earlier passages at paragraphs 43A to 43I of that statement of case. These claims also falls away save for any claim for compensation under paragraphs 43A(b), 43B, 43C and 43H, but only in so far as based on the alleged failure to rectify defects identified in the TAC.[61]Paragraph 49(c) of the amended counterclaim seeks damages for financial and reputational harm caused by the filing of bankruptcy proceedings in Bahrain. There is no plea of Bahraini law to support this claim (despite the opportunity taken to amend). Applying English law principles, although an action can lie for malicious presentation of a winding-up petition, there would need to be an absence of reasonable and probable cause for presenting the petition and malice or an improper motive on the part of the petitioner (see Partizan Ltd v O J Kilkenny & Co Ltd[1998] BCC 912). Neither have been alleged here and nor is there any evidence supporting such a case. In my judgment this claim also has no real prospect of success.

Conclusion

[62]In light of the above I grant summary judgment on part of the claim and also grant summary judgment so as to dismiss the counterclaim in part.[63]I will hear further submissions on the precise form of the order (incuding the correct figure for the principal judgment sum), the appropriate directions for the balance of the claim and the surviving part of the counterclaim as well as any other consequential matters, in so far as these cannot be agreed. One matter that I would invite the parties to consider is whether the part of the counterclaim that survives should be repleaded with proper particulars.