The claim, brought under the Consumer Rights Act of 2015 which paved the way for class action lawsuits, is being led by former financial ombudsman Walter Merricks.

The appeal to CAT comes after MasterCard lost a 10-year legal battle with the European Commission over the level of interchange fees levied on debit and credit card charges.

The legal firm handling the case, Quinn Emanuel, has raised £40 million to take the case to court.

The documents handed in to CAT inlude a report from independent expert economists and accountants that support the claim; and a detailed plan for managing the claim, including how the proposed class of 46 million consumers will be communicated with through a claims website, newspapers, magazines and social media.

High profile consumer groups such as Which? and MoneySavingExpert.com have also agreed to follow the progress of the proposed claim and keep consumers updated.

Merricks states: “MasterCard charged billion of pounds of unlawfully high fees for its sole benefit and to the detriment of consumers. It has already been found to have broken competition law, the basis of which was to protect consumers, and that cannot be disputed. There is no basis upon which MasterCard can contend that its card fees were not unlawful. I am confident that the CAT will authorise the claim to go forward, and I look forward to the opportunity to present our case. This is a watershed moment for consumer redress in this country.”

MasterCard is certainly taking the challenge seriously, ditching its usual team of legal advisors in favour of one of the most highly regarded ‘Magic Circle’ defence law firms, Freshfields Bruckhaus Deringer, to represent its case.

In a statement, MasterCard says: "Now that the claim has been filed, we will take time to review it in detail. However we continue to firmly disagree with the basis of this claim and we intend to oppose it vigorously."