“Both parties accepted that the legal approach to whether there is a 'discovery' is correctly set out in this first passage from the decision of the Upper Tribunal in Charlton v Revenue and Customs Commissioner[2012] UKUT 770 (TCC) at [37], where the tribunal said: '[37] In our judgment, no new information, of fact or law, is required for there to be a discovery. All that is required is that it has newly appeared to an officer, acting honestly and reasonably, that there is an insufficiency in an assessment. That can be for any reason, including a change of view, change of opinion, or correction of an oversight.' The UT continued in a second passage: 'The requirement for newness does not relate to the reason for the conclusion reached by the officer, but to the conclusion itself. If an officer has concluded that a discovery assessment should be issued, but for some reason the assessment is not made within a reasonable period after that conclusion is reached, it might, depending on the circumstances, be the case that the conclusion would lose its essential newness by the time of the actual assessment.' [61] I agree with the UT's approach in both passages.”
'The courts are ever mindful that their constitutional role in this field is interpretative. They must abstain from any course which might have the appearance of judicial legislation. A statute is expressed in language approved and enacted by the legislature. So the courts exercise considerable caution before adding or omitting or substituting words. Before interpreting a statute in this way the court must be abundantly sure of three matters: (1) the intended purpose of the statute or provision in question; (2) that by inadvertence the draftsman and Parliament failed to give effect to that purpose in the provision in question; and (3) the substance of the provision Parliament would have made, although not necessarily the precise words Parliament would have used, had the error in the Bill been noticed. The third of these conditions is of crucial importance. Otherwise any attempt to determine the meaning of the enactment would cross the boundary between construction and legislation …'
“My Lords, I shall now permit myself a general observation. Once it is fixed that there is a liability, it is antecedently highly improbable that the statute should not go on to make it effective. A statute is designed to be workable and the interpretation thereof by a Court should be to secure that object, unless a crucial omission or clear direction make that end unattainable.”