A photograph has been released showing the British-born head of security for a financial firm helping to evacuate the World Trade Center.

Shortly after the picture was taken, the south tower collapsed.

Rick Rescorla, 62, originally from Cornwall, is still listed as missing, presumed dead.

It is believed that he was helped in this valiant rescue effort by his colleague and second-in-command, Wesley Mercer. It is presumed they died together.

The number of British citizens who remain unaccounted for after the 11 September attacks has been revised down to about 200.

The photograph was taken by a secretary and shows Mr Rescorla trying to clear people on the 42nd floor.

Susan Rescorla: "Every day a miracle"

His colleagues at Morgan Stanley Dean Witter and other survivors have recalled how he tried to keep people's spirits up by singing and saying "God Bless America" as they left the building.

Mr Rescorla left Hayle in Cornwall aged 17 and trained as a police officer in London.

Aged 23, he went to America, where he became a citizen and joined the army.

He served as a lieutenant and platoon leader in Vietnam, where he was decorated for his courage and bravery.

Inoperable cancer

Mr Rescorla met his wife Susan when he was fighting inoperable prostate cancer and had been given six months to live

The couple married three years ago and since then he had stayed in remission.

She said: "I knew if I only had five minutes with him it would be the best five minutes of my life.

Rick Rescorla: Cornish roots

"We never tired of each other. Every day was a miracle."

She said her husband, a father of two, was a proud American, but never forgot his Cornish roots.

He regularly returned there and last visited in February this year.

After the tower was hit, he telephoned her on his mobile to tell her he was evacuating the building and that she had "made his life".

Mrs Rescorla is now planning a memorial for him at an American bird sanctuary, with a plaque bearing his name and a large cage just for great eagles.

"My Rick has spread his wings and has soared into eternity," she said.