The court agreed that the Competition Appeal Tribunal (CAT) made numerous errors of law in refusing to certify a mass consumer collective action brought by former financial ombudsman Walter Merricks.

The case is the first collective proceedings case of this kind to reach the UK Supreme Court. It addresses important questions about the correct legal requirements for certification of a claim.

Quinn Emanuel Urquhart & Sullivan LLP, representing Mr Merrick, said in a statement that the “historic and landmark judgment” had delivered a “decisive victory” for their client.