LAST week, Tony Blair secured the renewal of Trident only because the Conservatives supported him. A total of 95 Labour MPs were unwilling to support their own prime minister on an issue of national security. It was the largest defence rebellion in Labour history.

That this went by largely unmarked outside the Westminster village is an indication of how seriously things have deteriorated in the dog days of Blair.

There was a time, not that long ago, when it would have been unthinkable for a Labour leader to rely on Tory votes in this way. Failure to carry the Parliamentary Labour Party would have been a possible resignation issue.

Not any more. Instead we had the Labour chairwoman Hazel Blears popping up to congratulate the prime minister for winning "a majority of Labour backbenchers" - as if it was perfectly normal for the PM to fail to win the backing of his own MPs.

The contagion of conscience even spread to that most loyal of groups, the Scottish Labour MPs. Fifteen of them rebelled on Trident, including the chancellor's chum Nigel Griffiths, who resigned as deputy leader of the House.

The departure of the unnaturally ambitious Griffiths led to speculation about Gordon Brown's private views on Trident renewal. Would the pocket rocket have taken such a drastic step which nevertheless helps his prospects in his tight marginal Edinburgh South constituency, if there hadn't been a hint that Brown might be prepared to forgive this act of conscience and employ Griffiths in future? Only he knows.

And we may never find out, because the way things are going, Gordon Brown is unlikely to make it to Number 10. It's too early to say that the Tories have won an election that's more than two years away, but if Labour go on like this, they have certainly lost it.

The Cameron Conservatives have been returning their best polling figures since 1992, and this could become habit-forming. There is no law that says people can't start voting Tory again, in England at least.

Blair has done Brown and Labour a huge disservice by letting Cameron get his feet under the table at Westminster. The new Tory leader has grown visibly in stature and authority while the prime minister's have drained away.

And to add to Labour's woes last week, the Olympic costs tripled, Sir Hayden Phillips called for a cap on election donations from unions and, on a bad Blair day, Cameron's hairstyle upstaged the Climate Change Bill.

A collapse of Labour support in the Scottish elections in May could be the beginning of the end for Labour in the UK. The party has been piling up the negatives as if determined to alienate as many Scottish voters as possible. Trident is another nail in the coffin.

Renewal of the submarines, which will be based on the Clyde, was rejected by a clear majority of Scottish MPs - something the SNP will not let Labour forget. As we report today, one poll suggests that two-thirds of Scots believe it is unacceptable to station Trident here given the opposition from Scottish MPs.

The Blairites want to blame Brown for any Scottish disaster, and the Brownites want to blame Blair - but they are both likely to get a kicking. Labour's electoral credibility will be the first casualty. Following the Trident vote, there is nothing to stop the dissidents from dissing the party establishment.

It's not so long ago that rebellion on such a key issue as national security would have led to disciplinary action against errant Labour MPs. Or at least a severe spanking from the whips. That's not the case anymore.

Trident shows that Labour MPs can now exercise their consciences without fear of the consequences. That loss of fear is immensely significant. The systems of party discipline and authority that defined New Labour in the early years of this administration have broken down.

Remember the "pager clones"? They've gone the way of the electronic messaging device after which they were named. Labour MPs don't give a toss anymore and are increasingly becoming an opposition within their own government. Brown be warned.

Meanwhile, Blair is becoming a government leader in exile, relying on Conservative votes to impose policies - from university funding to defence - which his own party oppose. It's a weird reversal of roles.

The PM is so close ideologically to the Tories on education, Iraq, nuclear power, Trident, terrorism, attitudes to the White House and public services that there is almost a de facto coalition operating in Westminster. You wonder why Blair doesn't just cross the floor and be done with it.

If you were a conspiracy theorist, which, of course, I'm not, you might have wondered whether Blair has been a Tory mole all along. It's difficult to see how he could have made his departure more protracted and damaging to Labour if he'd tried.

SO, will Brown be able to put the party back together again? Restore discipline, provide vision and leadership? Inspire and enthuse a party which has lost the will to govern, if not the will to live? Possibly, but it's beginning to look like a lost cause for Brown. British voters don't favour divided parties - a house divided is a house defeated.

The chancellor, of course, is a towering intellect and one of the greatest politicians of his age - as he'll no doubt demonstrate in his last Budget on Wednesday - but he's looking old and tired. He has compromised on many of the key issues that are causing his party to disintegrate, including Trident, which he supported.

On issues such as defence, Brown is going to have to find some way of addressing the moral revulsion at the renewal of this system. My own view is that he may try to restore moral legitimacy by seeking to decommission Trident as part of the 2010 round of nuclear non-proliferation talks.

I see no evidence that Brown is interested in nuclear weapons for their own sake. Since there are no targets for this cold war weapon system, it would be logical to stop sending the boats to sea. This could be used as an inducement to other countries to disarm.

I can't help thinking that Brown would like to take a moral lead on nuclear disarmament, if he ever gets the chance. But then, what do I know? Nobody can see into the mind of Broon - a brooding enigma wrapped in a mystery. As on so many issues, the nuclear cards are held very close to the chancellor's chest. There is now a very real possibility that they will stay there, and Brown will take his secrets to the political graveyard.