"The next Ambassador Extraordinary and Plenipotentiary will be Louis Susman, a lawyer and financier with little experience in foreign affairs.

"The posting to London, to interact with America's supposedly close ally, has virtually become a retirement posting, offering a comfortable home in one of the best mansions in London, Winfield House in Regent's Park, and dinner invitations to Downing Street and Buckingham Palace.

"The recent crop of US ambassadors, since the career diplomat Ray Seitz left in 1994, have been political appointees more interested in talking about country walks or horses than Iraq or nuclear non-proliferation. Most of the diplomatic work is left to the number two and threes at the embassy, career diplomats.

"The appointment of Susman will end months of speculation. His name first surfaced in a diary column in the Washington Post in February but Caroline Kennedy was also mentioned as was Opray Winfrey, another of Obama's Chicago supporters.

"There was no official confirmation of Susman's posting today but the Guardian has learned that the all the necessary diplomatic paperwork been completed. Buckingham Palace this month approved the appointment and Obama is to make a formal announcement shortly.

"Susman, 71, a vice-president of Citigroup until he retired in February, has long been a financial backer of the Democrats, nicknamed the "vacuum cleaner" by the Chicago Tribune for his ability to hoover up campaign funding. 'I don't think anyone enjoys raising money, but for some reason I seem to have a knack for how to do it,' he told the paper.

"Susman, who lives in an expensive neighbourhood of Chicago overlooking Lake Michigan, raised at least $500,000 for Obama's campaign and a further $300,000 for his inauguration.

"The picks will disappoint former US career diplomats who have been pressing Obama to end the practice, especially since he promised to offer more of the top jobs to demoralised career diplomats.

"A retired diplomat with 30 years service, Morton Abramowitz, writing in the Washington Post in December, called on Obama to "publicly declare that he will not appoint ambassadors who have in effect secured their posts through financial contributions and who have little background to merit any such appointment".

"Ronald Neuman, a former career diplomat and ambassador and now president of the Washington-based American Academy of Diplomacy, sent a letter to Obama last year after he secured the Democratic nomination saying ambassadors should have demonstrated an interest in foreign affairs and, preferably, experience of the country they are being appointed to.

"Neuman said today: 'You would think with our most important ally we might occasionally send someone with some experience.'