I may as well get this not-especially-surprising opinion of mine into the open.
Blair’s made it clear that he disagrees with Parliament on what he takes to be an important matter of national security, and he seems to have contempt for the majority in Parliament which voted against his government’s plans. He chose not to seek a compromise with MPs that was there for the taking, which means that he was choosing yesterday to put his personal authority at stake in the crucial vote. In the circumstances, it’s not enough just to wander around muttering about how he hopes MPs don’t “rue the day” they voted the way they did.
There’s no reason to think there isn’t a stable majority in Parliament to stand behind a Labour government that is slightly less hostile to civil liberties than the current executive, slightly less keen on franchising out the public sector to the highest bidder, and slightly less keen to stand shoulder-to-shoulder with the Americans on dealings with the rest of the world.
Blair can now quit on a point of principle (and he badly needs a decent exit strategy of his own), and the Labour Party can set about sorting out a new leadership that can run the country in the time remaining between now and the next General Election.
(Oddly enough, Polly Toynbee has published an article on why Blair shouldn’t resign, which offers a number of good reasons as to why he should, and none as to why he shouldn’t, which is peculiar.)