William J Harrington was a senior analyst at the rating agency Moody's between 1999 and 2010 in New York.
Britain will be downgraded if the budget deficit rises because of weak growth.
Cabinet colleagues have warned George Osborne not to try to protect Britain's AAA credit rating because its loss is now inevitable and voters should be told it is unlikely to lead to higher borrowing costs.
George Osborne was warned by one of the world's three biggest rating agencies on Wednesday night that the UK will lose its prized AAA credit status if the UK sinks into a triple-dip recession this winter.
Global banks could face downgrades to their credit ratings as a result of the Libor scandal, the ratings agency Moody's warned on Tuesday as it emerged that the US department of justice had been in touch with traders at Royal Bank of Scotland.
Italian prosecutors on Monday requested that officials at ratings agencies Fitch and Standard & Poor's – including London-based staff – stand trial on charges of market rigging connected to their downgrading of Italy.
The UK has come a step nearer losing its AAA credit rating after one of the big three ratings agencies warned that rising debts and slowing growth jeopardised its status as a safe haven for investors.
US politicians came under renewed pressure to resolve a dispute over $1.2tn worth of spending cuts and tax increases after the ratings agency Moody's said it would probably cut its AAA rating if negotiations fail before a 1 January deadline.
The chancellor, George Osborne, has insisted that the world still has confidence in the British economy after a credit rating agency confirmed Britain's AAA rating.
Not good news.