William Thomas Stockler & Anor v The Corporation of the Hall of The Arts and Sciences

A party who accepts the figures for a costs bill after line-by-line assessment cannot later substitute different figures merely because subsequent calculations reveal alleged errors. An innocent misstatement may nevertheless be corrected under the slip rule or CPR 3.1(7), particularly where leaving the order unchanged would breach the indemnity principle.

A Part 36 offer remains valid despite minor errors which could not mislead a reasonable reader. Its costs consequences should be applied unless it would be unjust to do so. Indemnity costs for unreasonable conduct require behaviour which takes the case out of the norm, assessed in the round. The court may determine consequential issues on paper where the parties have had a fair opportunity to present their evidence and submissions.

The claimants, holders of permanent seats at the Royal Albert Hall, were the paying parties in detailed assessment proceedings concerning the defendant’s costs. Following line-by-line assessment, they accepted the defendant’s calculation of the bill, which was stated to total £120,513.88. They later applied to substitute a lower figure and alleged improper conduct by the defendant.

The court also determined liability for the detailed assessment costs, the consequences of a Part 36 offer, interest, the quantum of the defendant’s costs, and permission to appeal. The court had previously addressed proportionality in [2025] EWHC 2262 (SCCO). The central issues were whether the agreed calculation could be reopened, whether an arithmetic error should be corrected, whether Part 36 consequences applied, and whether the claimants’ conduct justified indemnity costs.

1. Application to substitute the bill calculation. The claimants had a proper opportunity to challenge the defendant’s figures after the line-by-line assessment. By stating that they assumed the figures were correct, putting forward no alternatives, and continuing with the assessment, they accepted both the total and its breakdown. The application to substitute different figures was therefore dismissed.
2. Correction of the defendant’s error. An inadvertent error had caused Part 2 of the bill to exceed the amount originally claimed. Leaving the order unchanged would breach the indemnity principle. The court therefore varied the order under the slip rule or, alternatively, CPR 3.1(7), applying the approach in Tibbles -v- SIG Plc [2012] EWCA Civ 518. The corrected total was £120,221.98.
3. Part 36. The defendant’s offer to accept £115,000 inclusive of interest was valid. Any defects in the form were minor and could not have misled a reasonable reader. The claimants had sufficient information and time to evaluate it, and no injustice was established under CPR 36.17(5). The Part 36 consequences therefore applied: standard-basis costs until 19 November 2024, indemnity costs thereafter, interest at 8% and then 14%, and an additional payment of £12,022.20.
4. Unreasonable conduct. Indemnity costs for unreasonable behaviour require conduct taking the case out of the norm. The court assessed the conduct in the round. Some points were misconceived or unhelpful but remained within the ordinary range of costs disputes. The pursuit of an inapplicable fixed-costs regime, the opportunistic recusal application, and the late amendments seeking to revisit matters already decided were unreasonable to a high degree. Indemnity costs were ordered from 23 June 2025, although the Part 36 order was the primary basis from 19 November 2024.
5. The defendant’s detailed-assessment costs were summarily assessed at £98,542.89. Permission to appeal was refused because none of the proposed grounds had a real prospect of success or disclosed a compelling reason for an appeal.

The judgment records earlier stages of the same detailed assessment proceedings, including the court’s earlier decision on proportionality at [2025] EWHC 2262 (SCCO). This judgment determined the remaining consequential issues and refused permission to appeal.