PRESIDENT George W Bush began his controversial state visit to Britain yesterday with a vow to bring peace and democracy to Iraq and the Middle East.

Amid the trappings of pomp and ceremony, President Bush made the only keynote address of his stay, telling an audience of foreign policy and defence experts that there would be no early coalition exit from Baghdad and no shrinking from his determination to spread US values across the globe.

Earlier, Mr Bush and his wife, Laura, had been officially welcomed by the Queen with a formal ceremony at Buckingham Palace - staged there rather than London's Horse Guards Parade for security reasons.

A 41-gun salute heralded the President and the First Lady, who had arrived on Tuesday night, as the full pageantry of a formal state visit unfolded.

Later, Mr Bush addressed the hard politics of his trip, with a speech at the Banqueting House in Whitehall.

He said there would be no backing down from the US-led mission in Iraq, despite the growing death toll among mainly US troops from terrorist attacks.

"We did not charge hundreds of miles into the heart of Iraq and pay a bitter cost of casualties and liberate 25 million people only to retreat before a band of thugs and assassins," he said.

The President stressed the "three pillars" on which he believed the peace and security of the free world were based. These were vigorous multi-lateral institutions such as the United Nations and Nato, the willingness to use force to overcome tyranny as a last resort, and the spread of democracy across the world.