By Jason Bennetto, Crime Correspondent

Published: 31 October 2005

One of the suicide bombers who attacked London on 7 July was filmed arguing with a cashier about being short-changed hours before he blew himself up.

Another of the terrorists – the teenager who destroyed a double-decker bus – was also captured on surveillance cameras wandering around the streets of London, "bumping into people", before detonating his rucksack bomb.

New details of the behaviour and last movements of the four suicide bombers, who killed 52 people, were disclosed by a representative of the Metropolitan Police Anti-Terrorist Branch, the magazine Police Review has reported.

The counter terrorist expert also told a seminar that the policing bill for the attacks on 7 July and the failed bombings on 21 July so far stands at