Held, appeal dismissed. The intention of Parliament and the public policy underpinning the introduction of the costs capping regime was the promotion of access to justice for claimants in judicial review proceedings which were “public interest proceedings” within the meaning of section 88 of the Criminal Justice and Courts Act 2015, and section 89(2) recognised the need to ensure reciprocity for defendants on their liability to pay the claimant’s costs. Sections 88 and 89 of the Act were intended to provide claimants and defendants with legal certainty as to the extent of their costs liability. The circumstances in which a CCO could be varied or revoked under CPR r 46.19 were fact specific. While there was no jurisdictional bar to the court making an order to retrospectively vary a CCO, such a variation would only be appropriate in exceptional circumstances. That approach was wholly consistent with the purposes behind the CCO legislation. The original CCO was a valid order made in accordance with the relevant provisions, which included the mandatory criteria in section 88(6) of the Act. While there was a subsequent change of circumstances when TI was granted legal aid for the judicial review proceedings, the fact of that change did not of itself invalidate the original order. There is nothing in section 88(6) which provided a basis to permitting revocation or retrospective variation of the CCO if the mandatory criteria were no longer satisfied. An application to set aside or vary a CCO had to be assessed upon its own facts and its merits. The appellate court would be slow to interfere with the exercise by a judge of a discretion particularly in respect of costs where the discretion was wide. The purpose of a CCO was not to ensure any particular level of remuneration for a claimant’s legal representatives. The application to set aside the CCO in the present case sought an order permitting the recovery at commercial rates and without any restrictions of costs already incurred and previously the subject of the CCO. Such an order would deprive the Director of the protection of the reciprocal cap which the Act required as part of the balance for TI obtaining a CCO. Such an order would undermine the concept of legal certainty which was an intention of the CCO regime and its practical effect would be to retroactively expose the Director to a significantly greater adverse costs liability in respect of costs already incurred and currently covered by the CCO. The deputy judge applied an approach which fairly reflected the balancing of the interests between TI and the Director of Legal Aid. There were no grounds to interfere with the order of the deputy judge varying the CCO. Accordingly, that order would stand unaltered (paras 36–42, 45, 46, 47, 48, 49, 50).