The finance watchdog has admitted that the number of 'mortgage prisoners' across the UK may exceed previous estimates. Mortgage prisoners are borrowers who took out high-interest home loans with lenders such as Northern Rock, which collapsed during the 2008 financial crash. Trapped in a catch-22 situation thanks to mortgage lenders' rules (see factbox below), they have been paying eye-watering interest rates of up to 9 per cent, in some cases for more than a decade. Trapped: Mortgage prisoners took out high-interest loans pre-financial crisis and find it difficult to remortgage due to stricter affordability criteria, debt and negative equity The Financial Conduct Authority has previously said that there are 250,000 mortgage prisoners, but the review will interrogate that figure.