Revealed: Britain's first victim in the war on terror

But a memorial on the wall of Thames House, the headquarters of MI5, tells a very different story.

For Steven Lanham, it can be revealed, was a hero - the first British agent to give his life in the global war against terror.

Disguised as a dispatch rider, the 39-year-old former soldier was on "close target reconnaissance" when he was killed in mysterious circumstances.

He was following a suspected terrorist on a powerful Honda superbike loaded with high-tech spy equipment when a car swerved across his path.

Mr Lanham suffered multiple injuries and died later that night in a London hospital.

A "Turkish or Arab" driver was questioned for hours at the secure Paddington Green police station, where terror suspects are taken for interrogation. But an inquest later ruled Mr Lanham's death was an accident.

Details of the crash in 1999, when few people had heard of Al Qaeda, are still shrouded in secrecy.

Scotland Yard's report lists it as a "motorcycle dispatch rider in collision with a car at 6.45pm on Prescot Street, London, E1".

Files on the inquest have been sealed under the Official Secrets Act.

But a clue that Mr Lanham was not who he seemed comes on his death certificate, which reveals he was a civil servant.

His value to MI5 was illustrated by the fact that the father-of-three's funeral was attended by hundreds of Security Service colleagues and the then chief of the organisation, Sir Stephen Lander.

But while proud of their son, Mr Lanham's parents still do not know the full facts of his death.

Mother Jean said: "Of course we'd like to know more about it, but Steve was doing secret work vital to the security of the country, so we don't ask questions.

"We aren't happy about it, but we're not angry either."

His father, Vic, added: "We were told that he was not deliberately killed and that it was an accident, but we don't know what to think because we have none of the facts. All we know is that our son was a hero and we're proud of him."

The pensioners were speaking at their bungalow on the South coast. Close to them, on the wall, are pictures of their son in a flying suit standing next to a military aircraft and a printed copy of the eulogy given at his funeral by a fellow MI5 officer.

And given pride of place is a picture of the Queen looking at the plaque in Steve's memory in Thames House.

It reads: "Steven Victor Lanham of the Security Service, who died on 13th October 1999 while on surveillance duty in London."

Mrs Lanham said: "We don't know much more than what is on the plaque. We did glean that he was following a terrorist suspect on his bike when a car suddenly swerved across the road, knocking him off.

"We were told that the driver was Turkish or Arab, and that he was taken to Paddington Green for questioning, then released.

We don't know if the driver was the same person that Steve was shadowing or whether the circumstances were suspicious.

We don't know if this person was in the country legally, a diplomat or a businessman, but we know he was a foreigner.

"The strong impression we formed is that Steve was working on an Al Qaeda type of terrorism, but no one has told us anything officially.

"Of course, we're immensely proud of our son and the work he was doing.

"I'd like Steve's courage and sense of duty and country to be an inspiration to others."

A eulogy from another agent delivered at Mr Lanham's funeral, echoes the couple's feelings.

His colleague said: "Steve was exceptionally good at his work and, in many ways, he was the bedrock of the team. He died trying to make our country a little safer for us all."

Steven Lanham was a keen horseman in his teens and, at 16, he joined the Household Cavalry, but instead of riding horses, he found himself driving tanks and armoured cars.

He did tours of duty in Northern Ireland and left the Army after four-and-a-half years to go to college to study engineering.

He later applied to join the police. His mother said: "Steve passed all the tests, but they said he was too quiet.

"But then he was approached by MI5 and offered a position with their surveillance team. We assume the police passed his name on.

"He never spoke about his work and that was fine with us. We knew the happier side of Steve.

The quiet, loving husband and father who liked doing DIY and doted on his wife and his children, Jessica, now 18, Jordan, 16, and Chantelle. nine.

"Four coaches full of MI5 staff came to his funeral including the head of the service.

"Many fine things were said, and we appreciated that. But a lot has happened since his death and we still wonder why he died."

Security sources would not be drawn on the exact circumstances of Mr Lanham's death, nor discuss the nature of the work he was doing.