Are the numbers against the would-be leaders?

In his victory speech a few hours ago, John Mason exclaimed that “this SNP victory is not just a political earthquake, it is off the Richter scale”. It’s hard to disagree. After all, overturning a 13,507 majority is impressive stuff, whichever way you slice it. So impressive, in fact, that it can only reinforce the idea that pretty much any Labour seat is now a viable target for opposition parties.

Which creates a particularly nasty conundrum for Labour MPs. Ousting Brown will become increasingly attractive, as he leads them towards oblivion in 2010. But many of the names being bandied around to replace him have smaller majorities than that overturned by the SNP last night. Here’s a selection of the would-be leaders, with their current majorities:

Jack Straw: 8,009
James Purnell: 8,348
Alan Johnson: 9.450
Ed Balls: 10,002
David Miliband: 12,312

Of course, this is a rather blunt way of looking at things – ideally, we should talk about swing, potential turnout etc.