At King's Cross, the revelations are greeted with disbelief and horror

The 54-year-old was queuing to sign the book of condolences outside King's Cross station - where four men arrived from Leeds to carry out last Thursday's bombings. "This is the kind of thing that happens in another country to someone else. It's a shock when it comes to your doorstep," she said.

The mood outside the station appeared to become more tense as people heard that suicide bombers were responsible. "This changes everything," said Martha Easton, 30, from Harrow. "If there are people willing to be that extreme, there is very little you can do to stop them. If you see an unattended package, you know what you're dealing with, but there's no warning with suicide bombers."

Commuters acknowledge that the newsmeant that British Muslims would be treated with suspicion. "I was on the bus on Monday and people froze when a Muslim woman got on," said Prudence Kaoma, a 25-year-old student."It was only when she got off [that] you felt the tension lift."

Fakhruddin Obri, 23, a marketing executive, said he expected people to view him differently. "I see it already," he said, "where people are so suspicious they stare at you. Hopefully it will get better with time."

Andrew Edwards, 40, a tribunal chairman from Hackney, said: "It just seems incredible. We'll have to look at what the Israelis do. They have a great deal of experience with this."

He suggested bag searches and security scans at ticket gates. But many questioned the need for "lock-down" security.

"The terrorists' real aim is to compromise our freedoms," said Ms Easton. "We mustn't give in to them."