Barack and Michelle Obama will pay a state visit to Britain between 24 and 26 May, in a trip designed to underscore US ties with Britain, and lay to rest more general doubts about the importance Washington accords to its European allies.
Details of the programme have not been released, but the Obamas will be the Queen's guests at Buckingham Palace. The President will hold talks with David Cameron and, if precedent is any guide, may also deliver an address to Parliament.
The invitation to Mr Obama, formally announced by the Palace in July 2010, was passed on by Mr Cameron during his first prime ministerial visit to Washington that month. Downing Street said Mr Cameron was delighted by the visit, calling it a sign of the "strong and enduring relationship between our two countries".
The Obamas were also in London for a G-20 economic summit in April 2009, but although they met the Queen and Prince Philip (and Mrs Obama raised eyebrows by putting her arm around the Queen) it was not a state visit.
The evident warmth of that encounter helped overcome the slightly rocky start to Anglo-American relations under Mr Obama. His decision to remove a bust of Winston Churchill from the Oval Office and replace it with one of his hero, Abraham Lincoln, was widely noted, and he never appeared to hit it off with Gordon Brown.
There was also much talk that the 44th President, born in Hawaii and part raised in Indonesia, had little interest in trans-Atlantic relations, and was especially cool on Britain, the former colonial power in Kenya, homeland of his father. Indeed, in some accounts, Mr Obama's grandfather was tortured by the British during the Mau Mau rebellion in the 1950s, during Mr Churchill's second and less glorious stint at No 10.
Mr Cameron's visit to Washington appeared to go well, despite being in the shadow of the April 2010 BP oil rig disaster in the Gulf of Mexico. Indeed, Mr Obama went out of his way to refer to "the special relationship" between the two countries, just as British parliamentarians and diplomats were trying to banish the phrase for ever. The state visit to London surely guarantees its resurrection.
In the first two years of his presidency, with the administration preoccupied with China, the Middle East, Afghanistan and Pakistan, relations with Europe have inevitably taken a back seat. But the state visit gives Mr Obama a chance to re-iterate the importance of ties with Washington's traditionally closest partners.
During the Queen's 59 years on the throne, she has met every incumbent US president except Lyndon Johnson. Oddly, Mr Obama will only be the second to pay a full-scale state visit. The first was by George W Bush in 2003, during the Iraq war controversy.