The end has come for Gordon Brown

Gordon Brown is finished. I said so on Newsnight last night and I say it again now with even more conviction. In James Purnell, he has lost a truly formidable Cabinet colleague, the best and the brightest of his generation, and one of the few senior Labour figures to grasp the full extent and novelty of the Cameron revival - much more than the neo-Blairite as which he is often caricatured in media profiles.

Purnell also has the countenance and personality of a future leader - as the Spectator tipped last year. I hope he reconsiders his statement that he will not run in the leadership election which must surely follow before long.

Number Ten will surely brief that Purnell was weighed down by difficulties over his expenses, or deranged, or both. It won't matter. This is a serious man resigning for serious reasons. Others will follow tomorrow.

So: the moment of decision has arrived for the timorous Labour tribe. Alea iacta est.