Sub prime mortgages most repossesed

Such mortgages are said to account for about 8% of the UK market.

But a study by Panorama and the Five Live Report of some 7,000 court hearings found that lenders who specialise in such mortgages or offer them as part of their business comprise over 70% of repossession cases.

The international "credit crunch" which affected Northern Rock was caused by the collapse of the American sub-prime mortgage lending market.

The BBC investigation into the sub prime market in Britain found some council tenants on benefits were being encouraged to seriously exaggerate their income to take part in "right to buy" schemes.

It also found families were given mortgages which within months they could not afford.

David and Maureen Bradbury, aged in their 50s, were given a 25-year mortgage worth £55,000 by London and Scottish Bank.

With their interest rate over 11%, the couple, who are on benefits and in poor health, struggled to make repayments and have faced repossession.

"I'm at the mercy of the interest rate," Mr Bradbury told the BBC. "If it goes up again, I'll struggle, I'll try and meet it. But after that if it goes up again I can't. We'll just lose the house."

London and Scottish told the broadcaster they follow industry rules regarding responsible lending.