Carr J. reviewed the cases on this topic and delivered a Commercial Court which is being followed widely at first instance.
‘Principles to be applied
36. An application to amend will be refused if it is clear that the proposed amendment has no real prospect of success. The test to be applied is the same as that for summary judgment under CPR Part 24 . Thus the applicant has to have a case which is better than merely arguable. The court may reject an amendment seeking to raise a version of the facts of the case which is inherently implausible, self-contradictory or is not supported by contemporaneous documentation.
37. Beyond that, the relevant principles applying to very late applications to amend are well known. I have been referred to a number of authorities: Swain-Mason v Mills & Reeve  1 WLR 2735 (at paras. 69 to 72, 85 and 106); Worldwide Corporation Ltd v GPT Ltd [CA Transcript No 1835] 2 December 1988 ; Hague Plant Limited v Hague  EWCA Civ 1609 (at paras. 27 to 33); Dany Lions Ltd v Bristol Cars Ltd  EWHC 928 (QB) (at paras. 4 to 7 and 29); Durley House Ltd v Firmdale Hotels plc  EWHC 2608 (Ch) (at paras. 31 and 32); Mitchell v News Group Newspapers  EWCA Civ 1537 .
38. Drawing these authorities together, the relevant principles can be stated simply as follows:
a) whether to allow an amendment is a matter for the discretion of the court. In exercising that discretion, the overriding objective is of the greatest importance. Applications always involve the court striking a balance between injustice to the applicant if the amendment is refused, and injustice to the opposing party and other litigants in general, if the amendment is permitted;
b) where a very late application to amend is made the correct approach is not that the amendments ought, in general, to be allowed so that the real dispute between the parties can be adjudicated upon. Rather, a heavy burden lies on a party seeking a very late amendment to show the strength of the new case and why justice to him, his opponent and other court users requires him to be able to pursue it. The risk to a trial date may mean that the lateness of the application to amend will of itself cause the balance to be loaded heavily against the grant of permission;
c) a very late amendment is one made when the trial date has been fixed and where permitting the amendments would cause the trial date to be lost. Parties and the court have a legitimate expectation that trial fixtures will be kept;
d) lateness is not an absolute, but a relative concept. It depends on a review of the nature of the proposed amendment, the quality of the explanation for its timing, and a fair appreciation of the consequences in terms of work wasted and consequential work to be done;
e) gone are the days when it was sufficient for the amending party to argue that no prejudice had been suffered, save as to costs. In the modern era it is more readily recognised that the payment of costs may not be adequate compensation;
f) it is incumbent on a party seeking the indulgence of the court to be allowed to raise a late claim to provide a good explanation for the delay;
g) a much stricter view is taken nowadays of non-compliance with the CPR and directions of the Court. The achievement of justice means something different now. Parties can no longer expect indulgence if they fail to comply with their procedural obligations because those obligations not only serve the purpose of ensuring that they conduct the litigation proportionately in order to ensure their own costs are kept within proportionate bounds but also the wider public interest of ensuring that other litigants can obtain justice efficiently and proportionately, and that the courts enable them to do so.
39 The Commercial Court has a long tradition of pro-actively managing litigation brought before it for the benefit of all users (as recognised, for example, in Worldwide Corp Ltd (supra)). The timetables laid out in and the requirements of the Admiralty and Commercial Court Guide, such as the requirement in D12.2 for provision of a progress monitoring information sheet, are designed precisely to avoid last minute problems which delay the start of trials or cause adjournment.’
This case is often cited at first instance. For a case in which the prospective amendments did not fall with Quah Su-Ling see Various Claimants v News Group Newspapers  EWHC 961 (Ch) under this tag.