The arguments over identity cards and detention without trial will take on a new urgency as ministers consider any new measures to take in the wake of the attacks.

There will also, needless to say, be questions over whether the war on Iraq made attacks on the UK more or less likely.

But the history of such terror attacks in the UK suggests that, in the short term at least, people are more likely to unite behind the government.

All these doubts and fears will be raised in the future. For now politicians are united with a common determination not to yield or indeed, over-react, to the bombings.