Millions of people around the world watched Ken Bigley begging for his life and urging Tony Blair to pull British troops out of Iraq in video film posted on the internet by his al-Qaeda captors.

For 22 days the fate of the Liverpool-born engineer, kidnapped in Baghdad in September 2004 by al-Qaeda’s leader in Iraq, dominated headlines and television bulletins. International leaders pleaded for his life, so too did his family, while his captors, led by Abu Musab al-Zarqawi, offered to negotiate with the British Government.

The kidnappers had always planned to kill him, as they did two American engineers seized with Mr Bigley, but the televised appeals only served their purposes and prolonged their hostage’s agony.

He was forced to record four videos, each more desperate than the last, including one of him chained inside a small wire cage in the kind of orange boiler suit worn by inmates held at Guantanamo Bay.

On October 7 Mr Bigley was beheaded.

The final minutes of his life were captured on film as he was forced to his knees and made to deliver a final statement. Then a masked captor stepped forward and severed his head with a butcher’s knife.

No television channel would broadcast the scene, but it was freely available on any number of extremist websites.

Professor Paul Wilkinson, the chairman of the Centre for the Study of Terrorism and Political Violence at the University of St Andrews, said: “That execution was deeply felt in Britain, as geography doesn’t count with such violence. Terror tactics that have worked in one place can easily be tried elsewhere. This is a classic method of spreading terrorist intimidation, using such tactics as hostage-taking as a theatre for intimidating a very large audience.”

The kidnap gangs require little more than a camcorder, knowing that their executions have a greater impact in the West than bombings and random shootings. These groups are always quick to admit responsibility.

Western governments have always sworn to hunt down those responsible, but the record on capturing them is poor.

When three British telephone engineers were beheaded in Chechnya on December 8, 1998, other Western contractors immediately pulled out of the area.

Many foreign workers, who were prepared to risk the threat of bombs and mortar attacks, pulled out of Baghdad when a video was released in May 2004 of the beheading of Nick Berg, 26, a businessman from Philadelphia.

Abdel Aziz al-Muqrin, the al-Qaeda leader in Saudi Arabia, warned all Western contractors to leave in June 2004 or suffer the same fate as Paul Johnson, an aeronautical engineer who was decapitated after being abducted in the capital, Riyadh.

His body was dumped soon after photographs were posted on an Islamist website showing his severed head on his body.

Many workers left their jobs, claiming that the rewards for living in Saudi Arabia were not worth risk.

An English public schoolboy from Wanstead, East London, Ahmed Omar Saeed Sheikh, helped to plan the kidnap of Daniel Pearl, an American journalist, in Pakistan in January 2002. The Wall Street Journal reporter was investigating the links that Richard Reid, the British shoe-bomber, had with al-Qaeda when he was lured into an ambush.

Omar Sheikh said that he handed his US captive to al-Qaeda, who beheaded Mr Pearl a month later.

A 3½minute videotape entitled The Slaughter of the Spy Journalist was released on the internet on February 21, 2002. The first part showed Mr Pearl stating his captors’ demands, the second, his throat being cut.

These websites not only carry violent propaganda but also instructions for making suicide vests, poison gases and explosives.

After the first British Muslim soldier was killed in Afghan-istan, militant websites denounced Corporal Jabron Hashmi, 24, as a traitor. One website, run by an extremist British group, al-Ghurabaa, posted a photograph of Corporal Hashmi surrounded by the flames of Hell.

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