By Nick Assinder
BBC News Online political correspondent
One of the most powerful post-war alliances
If ever there was a political match made in heaven it was that between Ronald Reagan and Margaret Thatcher.
There was an instant and genuine rapport between the two leaders which transcended the so-called "special relationship" between Britain and America.
With Ronnie in the White House and Maggie in Downing Street, the world witnessed one of the most powerful post-war alliances at work.
Hatred of communism
They supported each other through thick and thin, even when that meant risking attack at home, and it was impossible to tell who admired who the most.
In 1997, during a speech in honour of the former president, Baroness Thatcher described him as "one of the greatest men of our time".
In return, Reagan regularly heaped praise on her and, on one occasion as she was haranguing him over the phone, he remarked to an aide: "Isn't she marvellous?"
America supported British defence of the Falkland islands
They met and spoke together more often than any other post-war US and UK leaders with the possible exception of Churchill and Roosevelt.
The relationship was based on their common hatred of communism and their overwhelming desire to finally defeat the "evil empire", combined with a radical, free-market economic ideology.
For Britain and Mrs Thatcher, the relationship was proved beyond doubt when she won the president's unswerving support over the Falklands war in 1982, and his backing for economic sanctions against Argentina despite severe fears at home.
The following year, however, the relationship was put under strain when America invaded the former British colony of Grenada to oust the pro-communist junta.
Thatcher was reluctant to support the US invasion of Grenada
The invasion sparked outrage in the UK and Mrs Thatcher was reluctant to support the move against a Commonwealth member.
But the rift did not last, and just two years later the prime minister was engulfed in a major domestic row after giving permission for the US to launch a bombing raid against Libya from British bases.
The first anyone in Britain knew about the attack, which aimed to assassinate Colonel Gaddafi, was after it was over.
Mrs Thatcher's defence was simple. "When you're an ally, you're an ally," she declared. She continued to spark anger at home with her policy of allowing US nuclear missiles to be based on British soil and tying the UK nuclear deterrent in with America's.
The raid against Gaddafi was launched from UK bases
The relationship survived all these trials and more and continued long after the couple - and that is often exactly how they were seen - had lost power.
In 1998, Baroness Thatcher was presented with the Ronald Reagan Presidential Foundation's freedom medal by Nancy Reagan.
In accepting the honour, she declared it was "wonderful to have a medal named after a president who changed the course of history".