History of a special relationship

British Prime Minister Margaret Thatcher and President Reagan share a laugh during a meeting of the Allied leaders in New York on October 24, 1985. The defining image of British and U.S. relations by the end of the Cold War was of Prime Minister Margaret Thatcher and President Ronald Reagan. The grocers' daughter and the Hollywood film star struck up a rapport on the basis of their shared commitment to small government, economic liberalism and anti-communism. (REUTERS/Chas Cancellare) #

President Reagan drives Britain Prime Minister Margaret Thatcher toward their meeting in Camp David on November 15, 1986, after her arrival by helicopter from Washington. Even this relationship was subjected to strains, however. Thatcher was angered by the U.S. invasion of Grenada, a Commonwealth nation in 1983. In 2014 a recording of a phone call by Reagan, apologising to Thatcher, was released. (REUTERS/Anthony Hayward) #

President Ronald Reagan and Britain's Prime Minister Margaret Thatcher dance in the foyer of the White House during a State Dinner in Thatcher's honor November 16, 1988 in Washington. (REUTERS/Larry Rubenstein) #

British Prime Minister Margaret Thatcher and U.S. Vice President George Bush pause for the press on the porch of the Vice President's residence before a breakfast meeting November 15, 1986. (REUTERS/C. Combes) #

President Bill Clinton and Hillary sing the U.S. national anthem, standing alongside British Prime Minister John Major and wife Norma during a D-Day commemoration ceremony at the American Cemetery and Memorial in Cambridge June 4, 1994. (REUTERS/Stringer) #

President Bill Clinton toasts with British Prime Minister John Major during a formal dinner at the Prime Minister's official residence at No. 10 Downing Street, November 29, 1995. (REUTERS/Stringer) #

President Bill Clinton and British Prime Minister Tony Blair speak together during the NATO signing ceremony at the Eysee Palace May 27, 1997. (REUTERS/Charles Platiau) #

President George W. Bush (R) puts his hand on the back of Britain's Prime Minister Tony Blair (L) as they enter 10 Downing Street in London, November 20, 2003. The special relationship was reinforced again with the co-operation of Prime Minister Tony Blair and President George W. Bush over the Iraq War. (REUTERS/Russell Boyce) #

President George W. Bush shakes hands with British Prime Minister Tony Blair moments after receiving a note from U.S. Secretary of Defense Donald Rumsfeld given to him by National Security Advisor Condoleezza Rice informing the president "Iraq is sovereign" during the opening working session of the NATO Summit at the Istanbul Convention and Exhibition Center in Istanbul, Turkey, June 28, 2004. The president returned the note to Dr. Rice after writing, "Let freedom reign." Following the 9/11 attacks on the United States, Blair was keen to offer support to the United States. However, while the initial military action to depose Saddam Hussein as Iraq's leader in 2003 achieved its aims, the war became drawn out. The lack of weapons of mass destruction, which had provided a justification for the action, drew opposition on both sides of the Atlantic, with some describing Blair as a puppet of Bush. (REUTERS/Larry Downing) #

President George W. Bush and British Prime Minister Tony Blair leave the East Room of the White House after speaking to reporters about Iraq in Washington May 25, 2006. (REUTERS/Kevin Lamarque) #

President Barack Obama and Britain's Prime Minister Gordon Brown walk through the Colonnade at the White House in Washington, March 3, 2009. (REUTERS/Jim Young) #

British Prime Minister Gordon Brown smiles during a joint news conference with President Barack Obama at the Foreign and Commonwealth Office in London April 1, 2009. (REUTERS/Jason Reed) #

Britain's Prime Minister Gordon Brown and President Barack Obama leave 10 Downing Street in London April 1, 2009. (REUTERS/Toby Melville) #

President Barack Obama plays table tennis against students with British Prime Minister David Cameron at the Globe Academy in London May 24, 2011. Obama was popular in Britain and Prime Minister David Cameron was keen to portray their closeness, in contrast to the more awkward manner of his predecessor Gordon Brown. (REUTERS/Larry Downing) #

President Barack Obama and British Prime Minister David Cameron each eat hot dogs at a first round "First Four" game of the NCAA Division I Men's Basketball Tournament between Mississippi Valley State and Western Kentucky at the University of Dayton Arena in Ohio, March 13, 2012. Cameron high-fived Obama as they played table tennis during a visit to London in 2011, while Cameron ate hotdogs with the president as they took in a university basketball game in Ohio. (REUTERS/Larry Downing) #

President Barack Obama welcomes Britain's Prime Minister David Cameron aboard Air Force One as they depart to go to Ohio to watch one of the opening games of the NCAA Men's Basketball tournament, from Andrews Air Force Base, Maryland, March 13, 2012. However, Obama's comment in April 2016 that Britain would be "at the back of the queue" in trade talks should it vote to leave the EU also raised questions among Britons about the value of the relationship. (REUTERS/Jonathan Ernst) #

British Prime Minister Theresa May looks over toward President Barack Obama during the luncheon at the United Nations General Assembly in New York September 20, 2016. (REUTERS/Kevin Lamarque) #