TONY BLAIR’S future — and his programme of reforms — were called into doubt last night after MPs defeated him over the terror laws, inflicting a severe blow to his authority.

The Prime Minister, rocked by Labour’s first Commons defeat since he brought the party back to power in 1997, was facing the prospect of a year of rebellions as backbenchers gave warning that his “legacy” Bills on schools, hospitals and welfare were all under threat.

In a bitter personal rebuff, the Commons voted by a margin of 31 votes against his plan for the police to be allowed to hold terrorism suspects for 90 days. Instead they voted for the 28-day period favoured by the Conservatives, Liberal Democrats and many Labour MPs.

The blame for the reverse was laid firmly at Mr Blair’s door because it was his decision to opt for a vote on the 90-day detention period when other ministers appeared ready to compromise. Last night it appeared to have been one of the biggest miscalculations of his premiership. Had he offered a compromise — as Charles Clarke, the Home Secretary, indicated on Monday was likely to happen — the Conservatives would have been under pressure to accept it.

Forty-nine Labour MPs, including 11 former ministers, voted against the 90-day plan, a motion that the Government lost by 322 votes to 291.

Michael Howard, the Conservative leader, claimed that Mr Blair’s authority had “disappeared almost to vanishing point” and asked him to consider resigning.

Coming on top of David Blunkett’s second resignation and an outbreak of unprecedented Cabinet indiscipline, the defeat reinforced the image of a Prime Minister losing his grip on power. But, in a defiant response, Mr Blair attacked the MPs who voted against him.

“I have no doubt where the country is on this,” he said. “The country will think that Parliament has behaved in a deeply irresponsible way.”

Mr Blair could console himself with the knowledge that he had been beaten on an issue where he had the overwhelming support of the public and of the police.

But the defeat laid bare the frailty of his Commons majority as he proposes controversial reforms to weaken local authority control of education, to introduce more private sector provision of healthcare and to crack down on incapacity benefits abuse.

Within his own ranks Mr Blair, and anyone who follows him as prime minister, has to cope with around 30 “serial” rebels who can never be counted on to support him, except perhaps in a Commons confidence vote that would prompt a general election if he lost.

Senior backbenchers told The Times that Mr Blair would need the support of the opposition parties on all three issues to push his reforms through.

The overriding fear of the Labour whips was that, having tasted victory on an issue such as the terror laws, MPs will now be emboldened to defeat a weakened Prime Minister on the core policy areas.

Mr Blair said last night that he would not quit and insisted that he would not be defeated on his reform programme. He was disappointed to lose the vote but believed that he had done the right thing in putting the issue to Parliament.

Friends of the Prime Minister said that it was one of the most extraordinary votes in parliamentary history. One said: “Here you have a Labour Prime Minister being beaten because he supports the police and is in tune with public opinion and the Conservatives winning while being against the police and out of touch with public opinion. Is the world going mad?” It was noticeable that the Conservatives refrained from triumphalism after the votes were announced. One Conservative MP, Sir Peter Tapsell, voted with the Government and half a dozen others abstained, uncomfortable about being seen to be against the police.

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