"45. The procedure for the revision of costs budgets is set out inCPR r.3.15 A, which provides: '(1) A party ("the revising party") must revise its budgeted costs upwards or downwards if significant developments in the litigation warrant such revisions. (2) Any budgets revised in accordance with paragraph (1) must be submitted promptly by the revising party to the other parties for agreement, and subsequently to the court, in accordance with paragraphs (3) to (5). (3) The revising party must (a) serve particulars of the variation proposed on every other party, using the form prescribed byPractice Direction 3D ; (b) confine the particulars to the additional costs occasioned by the significant development; and (c) certify, in the form prescribed byPractice Direction 3D , that the additional costs are not included in any previous budgeted costs or variation. (4) The revising party must submit the particulars of variation promptly to the court, together with the last approved or agreed budget, and with an explanation of the points of difference if they have not been agreed. (5) The court may approve, vary or disallow the proposed variations, having regard to any significant developments which have occurred since the date when the previous budget was approved or agreed, or may list a further costs management hearing. (6) Where the court makes an order for variation, it may vary the budget for costs related to that variation which have been incurred prior to the order for variation but after the costs management order.' (Emphasis added) 46. Thus, the threshold criteria for the exercise of the power contained in r.3.15A are (i) there has been a significant development in the litigation since the last approved or agreed budget, which warrants a revision; and (ii) the particulars of variation have been submitted promptly to the other party for agreement, and subsequently to the court. It is only if these two criteria are met that the court goes on to consider the exercise of the evaluative judgment as to whether the budget should in fact be varied: Persimmon Homes Ltd v Osborne Clark LLP[2021] EWHC 831 at [99]-[101]. 47. In Persimmon Homes Ltd v Osborne Clark LLP Master Kaye stated (at [102]) that in relation to the exercise of discretion, the court must: '…have regard to the overriding objective and all the circumstances of the case including the need to deal with cases justly and at proportionate cost. This includes considering the prejudice to both the applicant if the budget is not varied and respondent if the budget is varied. The question of promptness and the nature of the significant development may come back into consideration more broadly as part of all the circumstances if the court comes to consider the overall exercise of discretion.' 48. Other relevant principles concerning the revision of costs budgets are: a. Where the significant development is said to be a change to an existing phase, it is necessary for the court to look closely at whether what is contended for is a significant development at all. In Persimmon Homes Ltd v Osborne Clark LLP Master Kaye stated (at [118]): 'In such a case the court would need to be confident that the proposed variation related only to the additional impact of what is contended to be a significant development rather than attempt to carry out a root and branch revision to the phases of the last approved budget. Whilst the court should not consider the costs at a granular level or micromanage the costs it must be able to say that it is not interfering with the discretionary exercise carried out by the Deputy Master who approved the last costs budget. It is for the party seeking the variation to provide sufficient information and evidence with their application to satisfy the court that the variation is not simply an attempt to address a miscalculation or an overspend or to claw back previously disallowed costs. They would have to be able to satisfy the court that the variation only related to the significant development and did not interfere with the exercise carried out by the Deputy Master.' (emphasis added) b. The decision to instruct leading counsel does not in and of itself amount to a 'significant development'. It is not enough for a party to regret, on reflection, not budgeting for instructing leading counsel. Nor is the test whether the seriousness of the case means it is suitable for leading counsel. The test is whether there is a significant development that warrants the instruction of leading counsel: Omya UK Ltd v Andrews Excavations Ltd[2021] EWHC 3824 (Comm) at [30] at [33]. c. Similarly, in Kimathi & ors v The Foreign and Commonwealth Office Parker Wall Solicitors[2018] EWHC 216 (QB) the court held that the party's decision to instruct new solicitors (because the previous solicitors became insolvent mid case and the work they had done was inadequate) did not amount to a 'significant development' in the litigation. Stewart J held (at [32]) that the defendant could not 'be required to pay extra costs for GT Law's insolvency, IC Law's intervention or the alleged inadequate work by GT Law, which is in any event disputed'. d. The fact that a costs budget as originally filed contains a mistake is not a reason for varying the budget. In Murray & Anr v Neil Dowlman Architecture Ltd[2013] EWHC 872 (TCC) Coulson J held at [17] and [19]: '17. … In my view, in an ordinary case, it will be extremely difficult to persuade a court that inadequacies or mistakes in the preparation of a costs budget, which is then approved by the court, should be subsequently revised or rectified… The courts will expect parties to undertake the costs budgeting exercise properly first time around, and will be slow to revise approved budgets merely because, after the event, it is said that particular items had been omitted or under-valued. I also agree that any other approach could make a nonsense of the whole costs management regime'. ... '19. ... I am not persuaded that the absence of prejudice alone would be sufficient (either in this case or more widely) to justify the revision of an approved budget. The whole basis of the recent amendments to the CPR is the emphasis on the need for parties to comply with the CPR, and the court orders made under it. It will, I think, no longer be possible in the ordinary case for parties to avoid the consequences of their own mistakes simply by saying that the other side has not suffered any prejudice as a result'. (emphasis added). See also John Michael Sharp v Sir Maurice Victor Blank & Ors[2017] EWHC 3390 (Ch) at [37]. "e. The fact that a variation will take that party's budget close to the other parties' budget is irrelevant. The question is whether the variations sought arise from, or are the result of, the significant development and not whether, on reflection, a party wishes they had budgeted more generously at the initial stage: Omya UK Ltd v Andrew Excavations Ltd at [19]."
"29. I turn now to the effect of the significant development and the costs that the defendants are seeking. A very significant proportion of the costs increase which the defendants seek is as because they contend it is appropriate to instruct leading counsel as a result of the significant development. The defendants argue that the nature of the case has changed as a result of the disclosure, because it is now clear from the disclosure that the Environment Agency are going to be involved, both in the disclosure exercise and also because one of their employees may give evidence. They argue that the defendants are now at risk of the Environment Agency revisiting its decision not prosecute the defendants and effectively to close its file, which it appears it made in about July 2019, so they defendants now need to instruct leading counsel. They argue the seriousness of the case has altered. "30. I do not follow the logic of that argument. It may well be that, on reflection the defendants regret not budgeting for instructing leading counsel. The test is not whether I consider the seriousness of the case means it is suitable for leading counsel. It is whether the significant development warrants the instruction of leading counsel. In my judgment it does not."