WH Holding Limited v London Stadium LLP

A party challenging an expert determination for manifest error must show more than a wrong or arguable contractual interpretation. Unless the contract provides otherwise, the error must be identifiable after an investigation limited in time and extent. It must be so obvious, and obviously capable of affecting the determination, as to admit of no difference of opinion. The court may use ordinary adversarial argument and admissible extrinsic evidence. A contractual mathematical formula receives the same test as other contractual language. The judge may first decide whether an error exists and then assess its obviousness. Where linked transactions may sensibly constitute one qualifying transaction, an arguable aggregation and pro-rating methodology is not manifestly erroneous, even if another interpretation may be preferable.

E20 granted WHH a long concession to operate football matches at the London Stadium. The agreement contained an overage provision requiring payment of a Stadium Premium Amount on qualifying transactions involving interests in the Club.

A transaction involved both the sale of shares and the grant of a call option. The expert treated them as one qualifying transaction and determined that WHH owed an additional £3.6 million. The High Court, in [2025] EWHC 140 (Comm), held that the determination contained manifest errors and was not binding. E20 appealed. The central issues were whether the expert’s interpretation and calculation were manifestly erroneous and whether the usual adversarial process could be used to establish such an error.

Phillips LJ gave the leading judgment, with Falk and Zacaroli LJJ agreeing. The appeal was allowed and the expert determination was declared valid and binding.

1. Manifest error. Parties who agree to be bound by an expert determination cannot ordinarily challenge it merely because the expert made a mistake. A material departure from instructions, fraud, or a contractually recognised manifest error may provide a basis for challenge: Campbell v Edwards [1976] 1 WLR 40; Jones v Sherwood Computer Services plc [1992] 1 WLR 277. The applicable test is whether, after investigation limited in time and extent, the error is so obvious and obviously capable of affecting the determination that it admits of no difference of opinion. An arguable error is insufficient. The formulation in Veba Oil Supply and Trading GMbH v Petrotrade Inc [2001] EWCA Civ 1832 was treated as reflecting that test, which had been approved in Sara & Hossein Holdings Ltd v Blacks Outdoor Retail Ltd [2023] UKSC 2.
2. Method of assessment. Limited investigation does not mean that the judge must decide the matter from the award alone or without adversarial argument. In a challenge to an expert determination, the ordinary process applies and extrinsic evidence is admissible unless the contract provides otherwise. The leave-to-appeal approach in Pioneer Shipping Ltd v B.T.P. Tioxide Ltd [1982] AC 724 concerned a different jurisdiction and procedure and was inapposite. A judge may first determine whether an error exists and then assess whether it is manifest.
3. Contractual formulas. There is no separate, more demanding rule for mathematical formulas. The same manifest-error test applies to contractual interpretation. The court must not substitute its preferred construction merely because it considers that construction potentially correct.
4. Application. The definition of qualifying transaction was wide enough to encompass the linked share sale and call option. The word or could arguably provide alternative calculation rules for different elements of one transaction. The expert was entitled to consider the commercial purpose of the overage provision and to aggregate and pro-rate the adjusted consideration in the manner adopted. That approach was arguable and not so obviously wrong as to admit of no difference of opinion. The determination was therefore not affected by manifest error.

• Court of Appeal (Civil Division). In [2026] EWCA Civ 153, the court allowed E20’s appeal and declared the expert determination valid and binding.
• High Court, Commercial Court. In [2025] EWHC 140 (Comm), the Deputy High Court Judge declared that the determination was affected by manifest error and was not final or binding.