The people who set off the bombs in London may have expected to get away:

one police hypothesis is that the bombers were tricked by a “master” who told them they would have time to escape – when in fact the devices were set to go off immediately.

“The bombers’ masters might have thought that they couldn’t risk the four men being caught and spilling everything to British interrogators,” an unnamed security official told the Telegraph.

Lending weight to the theory is the fact that all four men had paid up their parking tickets before boarding a train at Luton for King’s Cross, and that they all bought return tickets to the capital.

Moreover, the paper said, the men were carrying their explosives inside rucksacks, as opposed to strapped to their bodies as is common practice among suicide bombers.

None were reported to have cried “Allah Akbar” (God is Greatest) before setting off their charge – something which most Middle Eastern suicide bombers do.

If they were duped into it, as it looks like might be the case, it will make it harder for future recruitment, because bombers unwilling to sacrifice themselves may not trust their masters. Of course, this isn’t unprecedented. Bin Laden joked on the videotape about many of the September 11 hijackers having no idea why they were hijacking the planes.