The description comes from an Iraqi rebel leader who says he spent eight months collaborating with Abu Musab al-Zarqawi, the terrorist who this weekend holds the life of Bigley in his hands. Last week the rebel, called Abu Muawiya, agreed to speak to The Sunday Times about his former ally.

It is an al-Zarqawi trait, he said, to torture hostages by showing them how other captives have been beheaded. They are played gruesome videos to leave them in no doubt about what lies in store.

“Al-Zarqawi is ruthless in this,” he said, “and insists that it is not enough to kill them once, physically, when they are shot or beheaded, but that they should also be killed psychologically while they await their fate. It is killing them twice in effect.”

For a week now Bigley has been living this hell: he knows that the two Americans captured with him have been decapitated. He knows that at any moment his captors could come for him, force him to kneel in front of the camera and put the knife to his throat.

He probably knows, too, that he is just a pawn in a new, wider psychological war where the weapons are pornographic scenes of savagery.

“Beheading is a tactic to terrorise westerners and occupation forces,” said Muawiya, “and to terrorise the public at large and drive them to pressure their governments into pulling out of Iraq.”

As he spoke a video of the murder of the second American hostage played on a television. It began with a logo for Tawhid wal Jihad (TWJ), al-Zarqawi’s terror group. “The media department of Tawheed wal Jihad,” read the credit, “presents the beheading of the second hostage.”

A name flashed on the screen. Jack Kensley. It was a mistake: the victim’s name had been Hensley. A few background pictures followed and then a scene showing a man reading a statement, leaping at the hostage and taking a knife to his throat.

Such butchery and the desperate plight of Bigley suddenly rammed home the chaos in Iraq. The world, which had begun to shrug wearily at the endless bombings, was shaken out of complacency.

The pressures threatened to divide the allies. Spain and the Philippines had succumbed to terrorist demands. Now the terrorists were testing Tony Blair’s political will and religious faith to the utmost.

The horror cut deep into Blair’s psyche. Would the family man embrace the agony of Bigley’s relatives? Would the devout Christian come to the aid of the helpless hostage? Or would the statesman shut off those emotions, abandoning Bigley as expendable? Yesterday a website claimed Bigley had been beheaded, but his murder remained unconfirmed. Either way the war, as Blair averred, had entered a ghastly new phase. The battle for hearts and minds had utterly reversed.

It was no longer being fought by the allies in Iraq. It was being fought by the terrorists through the screens and pages of the media in the West. They intended to horrify voters into turning on the leaders who had embroiled Britain and America in Iraq — a venture Blair had promised would make the world safer.

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