The caller described how she had studied the photograph issued by Scotland Yard of Yasin Hassan Omar, whom she had seen carrying heavy cardboard boxes into No 63 for the past couple of nights.

She told how this tall, shifty-looking figure had been joined by three associates in moving bulging bin liners and bedding into the scruffy ground-floor flat.

The witness was fed up with being disturbed by this group who only ever seemed to shift items to and from their car in the small hours of the morning.

None of her neighbours had ever spoken to the gang but the gossip was that their behaviour was so suspicious that they they had to be up to no good.

The caller’s breathless account was sufficiently detailed for plain-clothes police to make a surreptitious visit to the tree-lined street in the Hay Mills area of Birmingham on Tuesday afternoon.

Careful not to be spotted, the officers studied the 1930s’ council houses and the Small Heath Recreation Ground that backs on to family homes in this ethnically mixed community.

Soiled net curtains covered the windows of No 63 and there was little sign of movement inside the ground-floor flat. Neighbours said that one of the regular occupants was a pregnant Somali woman.

The dilemma for the squad of MI5 agents and Scotland Yard anti-terror officers keeping watch overnight was whether to seize the man who had tried to blow up a Tube train at Warren Street or wait to see if his accomplices might join him.

Omar, 24, had last been spotted at his London flat on Friday afternoon, and then drove to Birmingham where, police say, he was met by other Somalis. Mandy Higginson, 57, thought that she had served another of the gang, Muktar Said-Ibrahim, at the local fish and chip shop, on Saturday lunchtime.

Other residents could not be sure if the man seen running away from Shepherd’s Bush was another visitor to No 63 since the abortive attacks last Thursday. Police and security chiefs decided that they dared not risk letting him escape and drew up tactics on how best to raid the property, believing that the terrorist inside would surely have explosives to hand.

At 4.30am yesterday, the raid began.Police from the West Midlands used vans to seal off surrounding streets. Armed MI5 agents and Metropolitan Police detectives poured out of unmarked vehicles.

One resident, Linda Walsh, 43, told how said she was woken by a volley of loud bangs. “I thought at first it must be gunshots,” she said. Peeking through the bedroom curtains she saw two orange flashes light up the night as an officer in riot gear fired stun grenades through the windows of the ground-floor flat opposite.

By then half a dozen plain-clothes officers had burst through the front door. A neighbour thought he heard the police shout “Hassan” once they were inside the suspect’s flat.

Police sources say that Omar, dressed in shorts and a T-shirt, had been lying on a settee. He made a grab for a dark rucksack lying on the floor a couple of feet from him.

One of the officers fired a 50,000-volt shock from a Taser gun at his chest amid concern that he had a device hidden inside his bag. Some eyewitnesses claim that police then dropped it out of the broken front window on to the lawn below. Tom Wheeldon, 86, who lives next door said: “I saw them bring my neighbour out and sit him on the front steps. He kept putting his hands to his head as if it really hurt.”

Andy Wilkinson, 42, who lives opposite, said that Omar was brought out of the flat in a white paper suit with plastic ties around his wrists and ankles 15 minutes after the raid began. He was bundled into an unmarked car and driven away.

Omar was known on the North London council estate for always wearing traditional Muslim dress. Mr Wilkinson’s wife Julie, 35, said that, in Hay Mills, he wore smart casual shirts and jeans.

She added: “I saw him rarely, maybe once a week, but in the last couple of weeks it has been really hectic with lots of coming and going from the house. I saw him each time accompanied by a couple of Pakistani-looking men who were possibly in their late 20s and also wearing casual clothes.”

Investigators believe that the terror cell had been using No 63 as a safe house for the past four months, supported by a group of other East Africans.

Police moved on to a second Birmingham address a mile away at Bankdale Road. Officers wrenched the front-door frame off as they arrested the three men inside. The trio, believed to be Somalis, were questioned in the West Midlands about links to the terror cell and to discover if bombers had picked Birmingham as their safe haven, or their next target.

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