Last week, it was all smiles and handshakes as Gordon Brown and President Barack Obama put on a show of unity in Washington.
But yesterday, Sir Gus O'Donnell, Britain's most senior civil servant, exposed transatlantic tension when he protested that Downing Street was finding it "unbelievably difficult" to plan for next month's G20 summit in London because of problems tracking down senior figures in the US administration. "There is nobody there. You cannot believe how difficult it is," the Cabinet Secretary told a civil service conference in Gateshead.
Last night Downing Street insisted the comments – reported on the Whitehall and Westminster World website – had been taken out of context. It added that Britain and the US had established a "very good and close working relationship" in the run-up to the G20 conference in London on 2 April. The Cabinet Secretary's undiplomatic language follows an outwardly-successful 48-hour visit by Mr Brown to Washington, which included talks with the new President and an address to the US Congress. The Prime Minister secured Mr Obama's backing for moves to kick-start the global economy, which he hopes to use to prompt other G20 leaders to support the fiscal stimulus package.
But Sir Gus's remarks will leave ministers smoothing feathers in the new administration, whose support is vital for agreement at the summit.
He made them as he stressed the importance of a permanent civil service rather than the US practice of filling posts when a new President is elected. He said it would be "madness" to introduce a similar system in Britain, because of the need for continuity in major projects such as the 2012 Olympics.
"You get to a certain point, and you can't go any further," Sir Gus said. "A whole new bunch of people come in who probably haven't been in government before." Fifty days after President Obama was sworn in, every senior post in the US Treasury Department remains vacant, with the exception of Timothy Geithner as Treasury Secretary, who should have 17 deputies. The vacuum has prompted complaints that it is struggling to deal with the most severe downturn since the 1930s.
Mr Brown's official spokesman said: "[Sir Gus] was explaining the benefits of the British system of having a permanent civil service. We have a very good and close working relationship with the United States on G20 and other issues. I think last week what you saw was an administration fully engaged on the G20. That is the sense we got."
The Cabinet Secretary's comments were removed from the website after the Government protested.