We are all familiar with this scenario. A case has been in litigation for 12 months since issue and trial is imminent. Try as you might, you cannot understand why the other side has advanced their case in a particular way, or overlooked an obvious cause of action or defence. Then... a week before trial, or even at trial itself, the penny drops and a late application to amend is made. The submission is always thus: "Whilst I appreciate it is inconvenient to the other side and I apologise to the court for the time that has been wasted, one has to apply the overriding objective. The White Book notes cite Cobbold v Greenwich LBC August 9, 1999, CA, which says "amendments in general ought to be allowed". To refuse the amendment would be a severe injustice to my client and the other side can be compensated in costs". And there you have it, amendment granted. Every one troops off home, to come back in six months time. Of course the compensation in costs never meets the full extent of the outlay and it is extremely difficult to explain to the lay client why this should be allowed. Whilst one has sympathy in cases where some new development has occurred that could not reasonably have been unearthed any earlier, for the most part these applications are necessary simply because the case has not been prepared properly.
I strongly suspect most advocates have read no more of Cobbold than the White Book cites and it is often relied upon to argue that demonstration of prejudice by the amending party is sufficient to succeed in an application to amend when it is, of course, only one factor.
In the recent case of Swain-Mason v Mills & Reeve  EWCACiv 14, January 20, 2011 the Court of Appeal has revisited this issue. Lloyd LJ, giving the unanimous decision of the court, referred to the case of Worldwide Corporation Ltd v GPT Ltd December 2 1998, CA, unrep, a pre CPR decision that was not before the court in Cobbold. He cited with approval the judgment of Waller LJ where he said:
"Where a party has had many months to consider how he wants to put his case and where it is not by virtue of some new factor appearing from some disclosure only recently made, why, one asks rhetorically, should he be entitled to cause inconvenience to other litigants? The only answer which can be given and which, [counsel for the applicant] has suggested, applies in the instant case is that without the amendment a serious injustice may be done because the new case is the only way the case can be argued, and it raises the true issue between the parties which justice requires should be decided. We accept that at the end of the day a balance has to be struck. The court is concerned with doing justice, but justice to all litigants, and thus where a last minute amendment is sought with the consequences indicated, the onus will be a heavy one on the amending party to show the strength of the new case and why justice both to him, his opponent and the other litigants requires him to be able to pursue it."
In light of this and the case of Savings & Investment Bank Ltd v Fincken  1 WLR 667, CA, which had cited Worldwide with approval, Lloyd LJ concluded in Swain-Mason:
"The approach set out in Cobbold seems to me to have been superseded in favour of one which is a good deal less relaxed about allowing late amendments" (para 78).
The practical effect of this is that parties need to be aware of the Swain-Mason decision to argue it against any opponents seeking to make late amendments. If you find yourself on the other side of this coin, as we all do from time to time, then the guidance from Worldwide, cited in Swain-Mason should be the focus of your supporting evidence. Although the cases make no mention of CPR 3.9 (relief from sanctions), it would seem that covering those sorts of issues would be a wise move.