Of the five permanent members of the Security Council, only Britain has given the United States unqualified support during a series of stand-offs with Iraq. Diplomatic Correspondent, Barnaby Mason, examines why:

The instinctive reaction of any British government is to back Washington in a crisis.

That goes back at least to the alliance of World War II when the two countries stood together in the face of tyranny. The relationship is backed up by a common language and a habit of co-operation in many fields, not least the sharing of intelligence.

In one crisis, at Suez in 1956, Britain took military action AGAINST the wishes of the United States, and that ended in a humiliating climb-down at Washington's insistence.

In contrast, the instinctive reaction of any French government is to take a different line from the Americans, though less stridently than under General de Gaulle.

Shared ideology

A warm reception for Mr Blair at the White House

Now, the traditional Anglo-American bond is intensified by the warm personal relationship between Bill Clinton and Tony Blair. They have hit it off in a way not seen since Ronald Reagan and Margaret Thatcher in the 1980s. Their thinking on social and economic policy is also close - Mr Blair described it as the politics of the radical centre.

A similar warmth has been seen in meetings between the American Secretary of State, Madeleine Albright, and the British Foreign Secretary, Robin Cook, with some effusive words of praise on each side.

A balancing act

Also important in the confrontation with Iraq is Mr Blair's desire for Britain to play a leading role on the world stage, not just in the European Union. Working with the United States is a way for a medium weight power to make its voice heard; the professionalism of British forces is a valuable asset.

Over Iraq, the European Union has previously been unable to agree on and pursue a coherent foreign policy. Britain has been reluctant to join in the thankless task of trying to pin down President Saddam Hussein to a workable deal which does not fully implement UN resolutions.

Historic responsibilities

There are other factors too. As a nuclear power Britain is particularly sensitive to the dangers of a ruthless leader getting his hands on weapons of mass destruction. The Labour government is also aware that, under the previous Conservative administration, Britain played a large part in the West's arming of Saddam Hussein in the 1980s.

In opposition, Robin Cook was prominent in Labour's attacks on the Conservative cover-up of the arms-to-Iraq affair.

Britain's historical relationship with the Gulf perhaps provides a final reason for its hard line on Iraq. The British administered or gave protection to a number of Arab sheikhdoms in the past.