Some days reverberate through political history. The assassination of JFK on 22 November 1963. New Labour's landslide victory on 1 May 1997. The attacks on the World Trade Centre on 11 September 2001. But where were you when you heard James Purnell was standing down from parliament at the next election? Um, er, I'm not sure. I don't remember. And it was only earlier today.

Nor do I remember where I was when he resigned from the cabinet last June – another much-hyped but, in the end, irrelevant "event" which generated a (temporary) political and media storm in the Westminster village. (Back then, the Guardian's Martin Kettle breathlessly described the resignation as "an immense and quite likely fatal challenge to Brown's already blighted premiership", adding: "In the history of Labour governments it can only be compared with Nye Bevan's departure from the Attlee government over prescription charges in 1951." Get a grip, Martin.)

Nine months on, the sensationalist pro-Purnell coverage continues. The Times, which broke the story this morning, described his departure as "another blow to the Labour leadership" (is anything not a blow to the Labour leadership these days?) and ludicrously referred to him as "one of the few remaining Blairites with a chance of becoming Labour leader". Meanwhile, I can only imagine the wailing, weeping and gnashing of teeth inside the Guardian's offices – the anti-Brown paper has provided a regular platform for Purnell since his self-enforced departure from ministerial office last summer.

The former work and pensions secretary joins a long line of Blairite ex-cabinet ministers who have decided to jump ship at the next election and avoid the tough slog of opposition – including Stephen Byers, Alan Milburn, Geoff Hoon and Patricia Hewitt. My response? Good riddance to them all – and, in particular, Purnell.

Don't get me wrong. His shift to the left on the backbenches has been welcome. But I, for one, cannot forget his nine-year parliamentary record. He was chairman of Labour Friends of Israel for two years, during which he accused leftwing critics of Israel of antisemitism. He was a committed supporter of the Iraq invasion, and of Lord Hutton's subsequent, whitewashed inquiry, during which he reared his head as a vociferous and unrelenting critic of his former employers, the BBC. In the recent expenses scandal, Purnell was outed as having avoided paying capital gains tax on the sale of his London flat and even claimed £395 from the taxpayer for advice from an accountant.

His ministerial record, meanwhile, earned him the admiration of the rightwing Spectator, which described him as "the best candidate to succeed Gordon Brown". As secretary of state for work and pensions, Purnell welcomed private sector initiatives and alienated the public sector workers. He was, claimed PCS union leader Mark Serwotka, "the worst secretary of state for social security this country has ever had the misfortune of having". Why? Because he constructed a punitive, pro-private sector welfare-to-work programme that failed to deliver the expected jobs, and launched various gimmicky initiatives – including threatening to make unemployed alcoholics seek treatment or lose their benefits and trying to use lie detectors to tackle benefit fraud – in a tired, Blairite attempt to look "tough" and "radical" on welfare reform.

His rebirth on the backbenches as a thinker and activist has also been hyped beyond belief. He may be clever but Purnell is by no stretch of the imagination a public intellectual, or Labour's 21st-century Anthony Crosland. I will always remember one very revealing exchange on Newsnight, in a debate between Purnell and party elder Lord Hattersley, shortly after the former's resignation last summer. Asked to define what he would do differently to Gordon Brown and what specific policies he was advocating, Purnell replied:

"I think what we need to do is to renew ourselves and I think that goes through idealism. I think it goes through going back to our basic principles and articulating them for today."

Sorry?

Even his much-discussed Guardian piece in January, which I welcomed, lacked originality – he borrowed many of his key proposals from the community-based alliance, London Citizens. And, amid the progressive rhetoric, he also chose to highlight that he had "argued in cabinet that we needed to talk about cuts. It was clear that some cuts would be needed". Really? Tell that to the 67 economists who wrote two letters to the Financial Times today.

So, as I said, and without wanting to sound vindictive or petty: good riddance, James. The government, the party and the taxpayer will be better off without you.