What comes next after the Downing Street years?

He has suggested that he might look for work in education or charity after leaving office but many observers believe he will find it difficult to wean himself off the challenge of high-level decision-making and may seek a role in an international institution.

Speaking to GMTV's Lorraine Kelly before the General Election, Mr Brown said: "If I couldn't make a difference any more then I would go off and do something else. Sarah and I may go off and do charity voluntary work."

In what was seen by some observers as a veiled rebuke to Mr Blair for his money-spinning post-Downing Street corporate appointments, Mr Brown added: "I don't want to do business or anything else, I just want to do something good."

But the ex-Chancellor has been touted for years for a series of international finance posts.

An alternative would be to resume his academic career. He was a university lecturer before becoming an MP.