Chancellor Gordon Brown has met George Bush face to face for the first time as the two men took part in discussions at the White House.
The US President and the UK's most likely next Prime Minister talked for around 30 minutes on issues including trade.
Number 11 aides were taken by surprise by the pair's meeting, with Mr Bush dropping in unannounced to join a meeting with US national security adviser Stephen Hadley.
Mr Brown is in Washington for a series of meetings involving the G8 and the International Monetary Fund.
It came as the Chancellor, the overwhelming favourite to succeed Tony Blair as PM this year, used an interview to hit out at celebrity culture.
Mr Brown, sometimes criticised for his public performances, said he believed Britain was moving on from a situation where people were "famous for being famous".
"People are moving away from that to what lies behind the character and the personality," he told The Guardian.
Mr Brown was also asked about speculation he could face a leadership challenge from Environment Secretary David Miliband, replying simply: "That's up to him."
