Assensus Limited v Wirsol Energy Limited

Costs ordinarily follow the event. A successful party’s refusal to mediate justifies a costs sanction only where the refusal was unreasonable, assessed by reference to the nature and merits of the dispute, settlement efforts, proportionality, delay, and the prospects of success. There is no presumption that mediation must be accepted.

Interest on costs may be ordered from the dates costs were incurred, commonly at a commercial rate, while a reasonable period may be allowed for checking a detailed bill. An interim payment on account should ordinarily begin with the approved costs budget. Non-budgeted costs require a separate, realistic deduction.

Permission to appeal requires a ground with a realistic prospect of success. A stay pending appeal depends on the interests of justice; an assertion that payment would stifle an appeal requires evidence.

This was a consequential judgment following the court’s judgment of 26 February 2025, in which all claims by Assensus Limited against Wirsol Energy Limited failed.

The court determined the parties’ submissions on costs, interest on costs, an interim payment on account, permission to appeal, and a stay of execution pending appeal. The principal issues were whether Wirsol’s refusal to mediate justified a costs reduction, how interest and the interim payment should be calculated, whether any proposed appeal had a reasonable prospect of success, and whether payment would stifle the appeal.

1. Costs. Costs followed the event. Under Halsey v Milton Keynes General NHS Trust [2004] EWCA Civ 576, refusal of ADR is an exception to that rule. The unsuccessful party bears the burden of showing that the successful party acted unreasonably. The relevant considerations include the nature and merits of the dispute, other settlement methods, ADR cost, delay, and prospects of success. There is no presumption in favour of mediation. Applying those considerations, Wirsol’s refusal was reasonable because its position was vindicated, meaningful settlement offers had been made, the parties’ expectations remained far apart, and mediation was very unlikely to succeed. No percentage reduction was made.
2. The costs of Wirsol’s own amendment were payable in any event. The costs of Assensus’s amended Reply were in the case. Costs otherwise followed the event.
3. Interest. Interest on pre-trial costs was ordered at 2% above base rate from payment until one month after delivery of Wirsol’s detailed bill. The court declined to apply the 8% Judgments Act 1838 rate until two months after delivery, because a substantial proportion of the costs exceeded the approved budget and a reasonable opportunity was needed to interrogate the bill.
4. Interim payment. Applying MacInnes v Gross [2017] 4 WLR 49, 90% of incurred costs below budget and 90% of budget where incurred costs exceeded budget were allowed for budgeted phases. Applying Cleveland Bridge UK Ltd v Sarens UK Ltd [2018] EWHC 827 (TCC), a separate deduction was required for non-budgeted costs. The interim payment was assessed at £407,913.39.
5. Permission to appeal. Permission was refused. The proposed grounds concerning an implied bonus term, unjust enrichment, Invoice 176, and the quantum of the bonus had no reasonable or realistic prospect of success. The judgment had addressed the pleaded claims, the statutory-interest claim failed on independent contractual and implied-term findings, and the challenges to factual and expert findings did not approach the high threshold for appellate interference.
6. Stay. The court had a broad discretion directed to the interests of justice. A contention that payment would stifle an appeal had to be established by evidence on the balance of probabilities. The limited evidence concerning ATE cover, assets, and liabilities did not establish that the ordered payment would stifle the appeal. The stay application failed.

First-instance consequential judgment following the court’s judgment of 26 February 2025, in which all claims failed. The citation of that earlier judgment is not stated in the judgment.