A PHONE call from a worried mother in Leeds trying to find her missing teenage son led police to unravel the identity of the London suicide bombers.

The call was one of thousands the police handled last Thursday morning. This particular call came at 10pm, more than 12 hours after the last explosion had ripped the roof off a No 30 bus in Tavistock Square. The woman caller gave the name of her son as Hasib Hussain, 19. She told how she had been unable to reach him on his mobile telephone.

Hussain had left his parents’ home on Wednesday evening saying only that he was visiting friends in London. The strain in Mrs Hussain’s voice was obvious as she was told to describe what he was wearing the last time the family saw him.

By the time of the call from Leeds, forensic teams had begun bringing the first bodies out of the bombed-out Tube trains and the bus to begin the arduous process of identifying the dead. As dusk was gathering, a masked officer on the bus was noting what each victim had been wearing.

The burnt and bloodied clothes of one young man were a match of the description given by Mrs Hussain. What was clear to the scientific teams was that the injuries the teenager suffered meant that he had to have been close to the bomb.

From their expertise, the teams also knew that these were the type of injuries that a suicide bomber would sustain, including instant decapitation.

Teams of police and computer specialists were already searching through hours of footage from CCTV cameras from around all the Underground stations and from buildings around Tavistock Square.

They were told to look for a distinctive coloured top worn by Hussain who, senior investigators now feared, was the first suicide bomber to strike in Europe. From then on officers were told to concentrate on CCTV film taken from King’s Cross station.

The investigation — codenamed Operation Thesis — believes that Shehzad Tanweer, 22, had hired a car in Leeds and driven to Luton with the other two men to join up with the fourth man. Tanweer told the car hire company that he would return the Nissan Micra the next day. They parked the car in the station car park.

The fourth, unidentified man, is believed to come from Luton, which has a sizeable Muslim population.

The four suicide bombers stayed overnight in the Bedfordshire town and boarded a Thameslink train the next morning, reaching King’s Cross at about 8.20am. A female passenger is understood to have told police that she saw the four men board the train. CCTV picked up Hussain amid the sea of faces hurrying to catch their trains. It was then just after 8.30am. He had a rucksack clutched in front of him.

What staggered those examining the film was that surrounding him were three other young men. They were all of similar age and appeared to be of Pakistani origin. No one scurrying across the station concourse paid much attention to this group of smartly dressed young men, who were all carrying similar-sized rucksacks.

For several minutes their heads were close together as they chatted. Without any elaborate farewells the four split up and went their separate ways.

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