Calls show depth of confusion on Tube

Operators, who receive one report after another, at first attribute explosions and "thick black smoke" to a power failure.

The dialogue is at times slow and laboured as the operator initially rejects the possibility of a terror attack.

The first calls played to the court reported perceived power failures but the emerging picture becomes more serious as the operator receives reports of a "bang", walking wounded and passengers in the tunnels.

However, a considerable amount of time elapses between the blasts and the moment staff at the control centre accept there may have been a series of bombings.

Shortly after the attack at Aldgate, one caller tells the operator: "We have just had a big explosion, there appears to be something ahead of the train on the track. We have evacuated."

The caller is unable to give more precise details.

"We are not aware that anyone has been injured yet. We have lost all power as well," she says.

In the next recording, the operator is heard calling emergency services but shows a reluctance to dispatch rescue workers.

"We don't want to send anyone at the moment," he says.

He adds: "We are not looking at an act of aggression at the moment."

Steve Gozka, manager of Edgware Road Tube station, rang London Underground's Network Control Centre (NCC) at 9.06am to repeat a request for the emergency services.

"Something's gone badly wrong down there," he says.

At 9.11am the NCC operator tells a member of staff at Russell Square station that they "didn't think (it was) terrorist".

This point is repeated when a worried manager at Morden station calls the control room at 9.32am to ask what was happening, only to be told it was "not believed to be terrorist-related".

But immediately afterwards the operator tells an official from the Railway Inspectorate: "I'm leaning towards terrorism at the moment, but I can't tell you that," he says.