Like almost everyone in Westminster, I certainly cannot claim to have predicted that James Purnell would announce that he's to stand down as an MP at the next election, as he has done today. But I can claim to be unsurprised, having rejected the cynical view that everything Purnell does -- including his call this week for ideological clarity in Labour -- should be seen through the prism of the party's leadership.

In an article for the Guardian on Tuesday, I wrote:

Purnell probably knows that in the eyes of Westminster cynics he can make no intervention that isn't interpreted as some sort of act of hostility towards Gordon Brown, if not a pitch for the leadership when and if it becomes vacant after the general election. But Purnell should be taken at his word when he expresses a desire to contribute to the thinking of "a clear ideological argument in the manifesto", and in his hope that his resignation claim -- that Brown's leadership makes a Tory victory "more, not less" likely -- is proved wrong. He should even, despite the slight sense of frustration, be believed when he says: "I'm happy where I am now."

This is for two reasons. First, Purnell is -- contrary to conventional wisdom -- highly unlikely to run for the leadership. This is because he is preparing to back the near-certain candidacy of his close ally and friend David Miliband. But second, because -- like Miliband -- he is a much more complicated Labour figure than his vacuous "Blairite" label suggests.

Purnell has many enemies, including some on the left, as almost all the comments under my CiF piece showed. But he is nothing if not honest. His resignation last June -- agree with it or not -- was one of the few brave and clear acts among the many moves by the many rebels opposed to the status quo in Labour.

A year and a half or so ago, in the early days of Purnell being touted as a possible leader, I asked him about it and he said, again with honesty, "I've got a decision to make" about whether he wanted that kind of personal reassurance and scrutiny. So, in that context -- and bearing in mind that, as I have said, he is preparing to back David Miliband for the leadership -- his announcement today is not surprising.

Genuinely, he wants to do something else with his life. Purnell should be applauded for that, even by those cynics who can't get their heads round his latest move.

PS: Some news reports are claiming this is a "blow" to Gordon Brown and Labour because, the theory goes, Purnell has realised the party isn't going to win the election.

This doesn't quite work. If Purnell was ambitious, he would have waited until Labour loses and then stood as David Miliband's running mate, or claimed a key shadow cabinet role in opposition. Is it not just possible he is sick of Westminster, a very small world where he has spent almost all of his working life so far?

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