The Prime Minister has long been an advocate of 25-year deals and his Chancellor Alistair Darling joined the chorus in 2007, but those who listened are now paying the price.
Borrowers who took the long-term plunge two years ago will be paying around 5.98 per cent for their mortgage.
This was against rates of around 5.34 per cent on two-year fixes in 2007, with those now remortgaging are looking at a potential two-year fix of four per cent or less.
Louise Cuming, head of mortgages at moneysupermarket.com, said: "Many of those people who listened to Gordon Brown must be crying into their porridge each morning.
"It underlines the danger of locking yourself in so long into the future. Not even Mystic Meg has a mortgage crystal ball.
"Borrowers stuck on a 25-year deal must now be thinking: 'Do I stick with a mortgage at around six per cent while I see my savings rates also dwindle - or do I take the unsavoury step of paying an early redemption charge of at least three per cent of the value of my mortgage?'."
By 2011, a borrower who took out a 25-year fixed term mortgage of £100,000 in 2007 can expect to be £4,200 worse off than someone who got successive two-year fixed deals.
Louise Cuming added: "The problem for those on 25-year fixed-term mortgages is that the early redemption charge they would pay now is likely to be even higher than the amount of extra interest they would have to pay over the next two years.
"It's not only the savers of Britain who are angry right now, but also many of those who are locked into a 25-year fix."
