There are always two separate stories to be told on the day of an important parliamentary vote. The first is about what will change in the country, and the second about the endless drama of party fortunes.
Tonight, at least, this is a relatively simple one. Brown's win means attacks on his leadership qualities will die down, at least for a short period. Barring unforeseen events or an exceptional run of luck they will be back, probably around the time of the party conference in September. That is infinitely preferable to the now hypothetical alternative. Had he lost, it would have been one more nail in a coffin that is increasingly covered in them. Regardless of Downing Street statements disassociating tonight's vote from Mr Brown's position, the chances of a leadership bid would have multiplied. The prime minister will be glad that has not turned into reality.
The story of this country's fortunes - the story historians are interested in - is neither simple nor short. In response to the constant danger of terrorism, Britain has adopted one of the most draconian anti-terrorist systems in the western world. The events of September 11th changed the politics of every country, but there are good reasons to argue that the changes it has provoked in Britain are more extensive and deep-seated than anywhere else.
There are, still, other ways it could turn out. It is quite possible the powers will never be used, although that seems unlikely. Alternately, they may well be used but only in a restrained and reasonable manner. Jacqui Smith says they will only be activated by a "grave and exceptional threat", and it's quite possible that phrase will be interpreted in a narrow and specific way - during a real and sustained attack to Britain or her interests overseas.
But the signs don't point that way. Firstly, if the phrase was to be interpreted that way by the executive, why not construct it in a narrower sense, such as the human rights committee's "public emergency threatening the life of the nation"? Historically, the executive has a tendency to submit vaguely worded legislation in order to give itself room to manoeuvre in the future.
Also, the government's record on defining terrorism is deeply unsettling. One only had to witness the arrest of elderly pacifist Walter Wolfgang under terrorist legislation at a Labour conference two years ago to know that these laws are not always being directed at people any normal person would classify as a terrorist.
There is a strong chance these powers could be used to imprisoned small swathes of the Muslim community - up to and including teenagers experimenting with unpleasant and extremist books. Suddenly, Britain would not look like the country we live in today.
Tonight's vote could, in the future, be seen to define the fortune of the Labour party and specifically Gordon Brown. It was certainly one of those rare moments in parliament when Britain decided what kind of country it will be over the coming years.