The fees became a subject for consumer rebellion last year after the OFT ruled that similar fees for late and unpaid credit card repayments were unlawful, and consumer groups started to encourage customers to claim refunds.
More than 1m reclaim letters were downloaded from websites, and in some cases customers were able to win back thousands of pounds from the banks, who refused to contest the claims in court.
Martin Lewis, founder of the website Moneysavingexpert.com, told Sky News the ruling was "a massive vindication for bank charges campaigners".
He said up to £9bn could now be reclaimed by bank customers.
Let\’s rip £9 billion of capital out of the banks in the middle of a credit crunch!
Update: this seems to have been misunderstood. I\’m not arguing that the banks should not have to obey the law: of course they should. I\’m not trying to argue that it should be set aside or ignored, far from it. I\’m solely commenting on the point that in the grander scheme of things about bank solvency ratios and the like, this isn\’t exactly the most glorious time for this to happen. It never rains but it pours etc.