By Laura Miller
Gordon Brown will today kick off a round of meetings with world leaders as they begin their descent on the Capital in preparation for crisis talks at the G20 on Thursday.
Guided by an RAF escort, Air Force One will fly President Obama into Stansted airport for his first UK visit as president at 19:45 BST.
The president will then be whisked to the lawn of the US ambassador's residence in Regent's Park via helicopter, where he will be hosted by Mr Brown.
The PM is also scheduled to meet Australia's PM Kevin Rudd, president Yudhoyono of Indonesia, and president Lee of Korea.
At 11:00BST Mr Rudd will join Mr Brown for a debate at St. Paul's Cathedral entitled 'My Word is my Bond? Rebuilding Trust - the G20 and Beyond'.
Later Mr Rudd will attend a memorial service at Westminster Abbey in remembrance of the victims of the bush fires in Australia last month.
The two PMs will then be joined by President Yudhoyono and leader of the Conservatives David Cameron. The Indonesian president is set to deliver a talk at the London School of Economics at 15:30 BST.
Another round of handshakes is expected at 16:15 BST, when president Lee of Korea arrives at No.10.
Over the next two days Mr Brown's calendar will be marked by a series of visits and talks as he guides his guests around London.
Tomorrow will see the PM hold talks with the US president, before a press conference at the Foreign Office, followed by a 'working dinner' at Downing Street for all the visiting world leaders.
Spouses will arrive for a separate dinner later.