The electorate may be getting ever more used to its representatives facing criminal charges, but it's still acutely embarrassing for Harriet Harman, a QC and former law officer, to face prosecution over her involvement in a car crash in her constituency.

In the past, senior politicians who have faced criminal charges, such as Jeffrey Archer and Jonathan Aitken, have always stood down in order to fight their case.

She may well be found innocent, but if not, this incident will put paid to any residual hopes she had of winning the Labour leadership. It increasingly looks as if the leadership election will be a fight between the "Blairite" David Miliband and the "Brownite" Ed Balls.

Among those who would be most disappointed by Harman's downfall are the Tories. They view her as a unique figure in British politics: the only politician who could boost their lead over Brown.

To her credit, Harman has responded to this by developing a neat line in self-deprecation, once quipping at PMQs that "there aren't enough airports for all the men who would want to flee the country" should she win.

Harman was one of the few senior Labour figures to put the case for redistribution and progressive taxation in the pre-crash days. Let's hope she survives.

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