“39. In my judgment, this jurisprudence permits the following conclusions to be drawn: (i) Despite occasional references to a possible distinction between jurisdiction and discretion in the operation ofCPR r.3.1 (7), there is in all probability no line to be drawn between the two.The rule is apparently broad and unfettered, but considerations of finality, the undesirability of allowing litigants to have two bites at the cherry, and the need to avoid undermining the concept of appeal, all push towards a principled curtailment of an otherwise apparently open discretion. Whether that curtailment goes even further in the case of a final order does not arise in this appeal. (ii) The cases all warn against an attempt at an exhaustive definition of the circumstances in which a principled exercise of the discretion may arise. Subject to that, however, the jurisprudence has laid down firm guidance as to the primary circumstances in which the discretion may, as a matter of principle, be appropriately exercised, namely normally only (a) where there has been a material change of circumstances since the order was made, or (b) where the facts on which the original decision was made were (innocently or otherwise) misstated. (iii) It would be dangerous to treat the statement of these primary circumstances, originating with Patten J and approved in this court, as though it were a statute. That is not how jurisprudence operates, especially where there is a warning against the attempt at exhaustive definition. … 41. Thus it may well be that there is room withinCPR 3.1 (7) for a prompt recourse back to a court to deal with a matter which ought to have been dealt with in an order but which in genuine error was overlooked (by parties and the court) and which the purposes behind the overriding objective, above all the interests of justice and the efficient management of litigation, would favour giving proper consideration to on the materials already before the court. This would not be a second consideration of something which had already been considered once (as would typically arise in a change of circumstances situation), but would be giving consideration to something for the first time . On that basis, the power within the rule would not be invoked in order to give a party a second bite of the cherry, or to avoid the need for an appeal, but to deal with something which, once the question is raised, is more or less obvious, on the materials already before the court.”
“… a party must bring forward an argument on all points reasonably available to him at the first opportunity … to allow him to take them serially in subsequent applications would permit abuse and obstruct the efficacy of the judicial process by undermining the necessary finality of unappealed interlocutory decisions.”