By Chris Summers BBC News Online, in central London

The sun shone as brightly as it had on that fateful New York morning a year ago.

The instruments of the US Air Force Band glinted as they played God Save The Queen, followed immediately by The Star Spangled Banner.

Dozens of Britons and Americans had come to this quiet corner of central London - opposite the US embassy - to commemorate the 3,025 people who died in the attacks on 11 September 2001.

The US Army, US Air Force, US Navy, New York Police Department, RAF, Metropolitan Police and London Fire Brigade were all represented.

There were members of the diplomatic corps, US embassy staff, government ministers, the Leader of the Opposition Iain Duncan Smith and the former First Lady Rosalyn Carter.

By the mercy of God I overslept and missed my appointment in the South Tower - I had a lot of guilt as a result of that

Glenn Henderson Holidaymaker from New York

They were joined by ordinary people from all walks of life and both sides of the Atlantic.

Many wore the Stars and Stripes as a bandanna or a headscarf. Others wore tiny badges showing both the British and American flags.

Weeping

Some wept during the speech by Lieutenant Frank Dwyer, a New York police officer who helped in the rescue operation after the two planes slammed into the Twin Towers.

Among those listening was Glenn Henderson who would not have been standing where he was had it not been for serendipity.

Glenn Henderson survived because he over-slept

The computer consultant from New York over-slept on the morning of 11 September 2001 and was late for a meeting in the South Tower of the World Trade Centre.

He told BBC News Online: "I was driving in and was about 10 minutes away when I heard on the radio about the first plane hitting.

"Fortunately the woman I was supposed to be meeting survived, although she was badly shaken, but I lost two friends in the disaster.

"By the mercy of God I had over-slept that day and missed my appointment. For several months afterwards I felt a feeling of guilt, I could not help thinking that if I had been there I may have been able to save someone or just comfort them."

'Solidarity'

In his speech the US Ambassador, William Farish, paid tribute to the British as "America's truest friends", adding: "We gather here in solidarity - united in our determination to wipe terrorism from the face of the Earth."

Among those Britons who had helped were three Hampshire Police officers who travelled to New York in the aftermath of the attacks to counsel the relatives of British victims.

WPC Jackie Drake is a trained family liaison officer from Farnborough who usually counsels the relatives of victims of murder, rape and other violent crime.

We love the Brits - that is one of the reasons we wanted to be here today

David De La Cuesta Tourist from California

She said: "After the initial grief, what a lot of the relatives needed was some sort of closure. So the discovery of a body part which could be DNA tested, or a piece of wallet or credit card was terribly important to them."

She and her colleagues, Detective Constable Dave Williamson and Detective Inspector Alan Purvis, now feel a strong affinity for New York and what it has been through.

'Heal the wounds'

WPC Drake said: "Events like this today will help to heal the wounds."

David and Sandy De La Cuesta, from Morgan Hill, California, were on holiday in the UK but they felt they had to come to Grosvenor Square.

"We love the Brits. That is one of the reasons we wanted to be here today. We wanted to be somewhere where we could feel involved."

David Blunkett (right) said Britain had stood by the US in her darkest hour

Kyle Wilkins and his wife Leigh had brought their daughters, Rigby, nine, Reagan, seven, and Ryan, three, along to the ceremony.

All three girls were dressed in identical Stars and Stripes t-shirts and Mr Wilkins, who hails from South Carolina but lives in London, said it was important to bring them along.

He said it had been hard to explain to them the events of 11 September, adding: "It was important to tell them there are good people and bad people and you can't always tell between them so you have to be apprehensive."

Mr Wilkins said an initial outpouring of empathy and pro-American feelings in Britain after the attacks had waned in recent months.

Special relationship

"There are anti-Americans here, just as there are everywhere, but Britain has generally been very pro-American."

It has been an emotional day for all Americans

It was that "special relationship" which the Home Secretary David Blunkett referred to in his speech.

He said Britain had been there for US in her darkest hour just as the Americans had been during the Blitz.

Standing in the shadow of a statue of Franklin D Roosevelt, he quoted the former president: "The only limit to the realisation of our dreams of tomorrow will be our doubts of today. Let us move forward with strength and active faith."

Click here to watch people in London give their views about 11 September