By James Kirkup
12:54PM GMT 11 Dec 2012
As a result, many customers could be in line for repayments of interest. The error will cost Northern Rock, which was state-owed at the time, an estimated £270 million or an average of £1,776 per borrower.
Most of the customers concerned borrowed less than £25,000, Mr Osborne told MPs. Those affected will be receiving letters from Northern Rock shortly, he said.