At first, the anthem, played by the band of the Coldstream Guards, was heard in a hushed silence and then slowly, one by one, many started singing until the words of The Star Spangled Banner echoed across Green Park.  As the final notes of the anthem faded away, the musical tribute from the British armed forces, so warmly welcomed by those present, was greeted by a round of applause before a two-minute silence was observed.  Traffic on The Mall, one of central London's busiest thoroughfares, came to a halt during the tribute.  Standing rigidly to attention in the palace courtyard in front of the troops from the Coldstream Guards and the 1st Bn, the Devonshire and Dorset Regiment, the Duke of York, representing the Queen, took the formal salute.  Beside him, with hand on his heart, stood William Farish, the American ambassador to Britain.  The band then played a selection of sombre American music, including Hymn for the Fallen, written by the composer John Williams and used in the final credits of the film, Saving Private Ryan.  Although it was a brief tribute to those who had died across the Atlantic, most of those present, many of whom had been prevented from returning home by the grounding of flights to North America, said that it had enabled them to "come together to mourn".  Some Americans carried the Stars and Stripes flag while others held graphic colour newspaper photographs of the devastation in New York and Washington.  Jenny Lee, 31, from San Francisco, saluted and waved a cardboard flag she had made herself as the anthem was played.  "I was really touched that the Queen has done this. Even though I'm so many miles from home, I feel that Britain is really with us on this one," she said.  Susan Kramer, 54, who had been on holiday in Britain for two weeks and had lost friends in the New York attack, said: "This shows that the world is sticking together. Britain and America have always been close and this reinforces it.  "It was very meaningful that another country would honour our national anthem like this. I have felt pretty helpless up to now, because I have not been able to return home and I wanted to be with some other Americans."  Jim Lagos, on holiday from West Virginia with his wife Vicki as part of a group of 16, said: "It was highly emotional occasion for us.  "I found out about this from a taxi driver, who said, 'You know, all us Brits are with you'. It means so much to us. I found it very supportive."  His wife added: "I always cry when I hear the national anthem. To hear it here with the support of all these people is very touching."  Susan Young, 59, of St Louis, Missouri, said it had been "awe-inspiring" to watch the ceremony.  She said: "It's good over evil. But freedom will prevail. It's a war against civilisation. Our nations need to unite. We hope it's reciprocal for all the good we have done throughout the world."  The Queen returned later to Buckingham Palace from Balmoral, where she had been on holiday, to meet the American ambassador and his wife to offer her personal condolences.
IT is a military ceremony that has been performed countless times at Buckingham Palace but rarely has the Changing of the Guard evoked so much emotion for American ex-patriates in London and transatlantic visitors alike.