Ahead of their first meeting today (Friday January 26), here is look back at photographs of past US and UK leaders togethers.
Margaret Thatcher and Ronald Reagan
During Mr Reagan’s presidency from 1981 to 1989, the former President and Mrs Thatcher developed a great friendship built on trust and mutual respect.
The world leaders liked each other, sometimes danced together at state occasions and were often pictured in deep conversation at official events.
Instead of using formal language, they started their letters to each other in a familiar way with “Dear Margaret” and “Dear Ron”.
UK Prime Ministers and US Presidents in pictures: A look back at the UK-US special relationship
Margaret Thatcher and Ronald Reagan at an economic summit in Versailles, France, in 1982.
History of a special relationship: Presidents and Prime Ministers together
Wed, January 25, 2017
Ahead of the meeting between Theresa May and Donald Trump, a look back at the close ties between the U.S. and Britain.
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Margaret Thatcher shares a joke with Ronald Reagan, at No. 10 Downing Street
Tony Blair and George W Bush
The former Labour Prime Minister and George W Bush were great allies and referred to each other informally.
The two world leader hit it off immediately during their first Camp David summit in 2001.
Tony Blair assured Bush that he would be with him “whatever” – even before the decision to go to war in Iraq.
Tony Blair and Bill Clinton
When Bill Clinton congratulated Mr Blair on his election victory in 1997, the new Prime Minister replied: "You showed the way".
The world leaders worked closely on the Northern Ireland peace process. Mr Clinton repeatedly promised Mr Blair that he would say whatever he wanted him to.
George W Bush and Tony Blair at Camp David in February 2001
George W Bush and Tony Blair walk away after speaking to reporters about Iraq at the White House
Bill Clinton and Tony Blair during a NATO signing ceremony at the Elysee Palace in Paris
David Cameron and Barack Obama
Former US President Barack Obama revealed frustrations with British foreign policy under David Cameron’s leadership.
Before Mr Obama left the White House, his final phone call was to German Chancellor Angela Merkel. He described her as his ‘greatest partner’.
Gordon Brown and Barack Obama
The two world leaders worked together on the fallout from the financial crisis in 2007.
Mr Obama attacked Gordon Brown’s decision to release the man convicted of the Lockerbie bombing, Abdelbaset al-Megrahi.
David Cameron and Barack Obama joke as play table tennis in London 2011
Barack Obama and Gordon Brown at the the G20 leaders' summit in London in 2009
John Major and Bill Clinton at the White House in 1993
George H Bush and John Major at the London 17th G7 Summit in 1991
John Major with Bill Clinton and George H Bush
Unlike Mrs Thatcher and Mr Reagan, John Major did not forge a close relationship with Democratic President Mr Clinton.
His dealings with Mr Clinton were damaged by the fact he backed Republican former President George H W Bush in the 1992 presidential race.