There could be one of any number of reasons for the suspicious timing of this complaint: revenge for the Tory's huge success with the "Brown is a liar" theme, with Mandelson (who's caused huge problems for Osborne before, lest we forget the Russian yacht incident of 2008) its chief schemer. Or it is the opening salvo of a tit-for-tat exchange which will escalate and could go nuclear, resulting in vast political casualties and further constitutional fallout.
The complaint to the Parliamentary Standards Commissioner came from the chairman of the Labour Party in Mr Osborne's Tatton constituency, Laurie Burton.
In a letter to Mr Burton confirming that he will investigate the complaint, John Lyon said: "In essence, your complaint is that between 2001 and 2003 Mr Osborne wrongly identified his main home for the purposes of his claims against the Additional Costs Allowance, and that from 2003 Mr Osborne claimed for mortgage payments that were not necessarily incurred contrary to the rules of the house."
Mr Lyon said he would write to Mr Osborne and ask for his comments.
There are other possibilities, for example that this is yet another cynical, desperate Labour ploy (the complaint will most likely not be upheld) to hijack a political news agenda increasingly dominated by further terrible recession data, a growing government funding crisis, the prospect of another bank failure and the dishonesty of Gordon Brown. It will fail because, first, of the suspicion that this is a weak complaint: why, for instance, wasn't it made sooner. Second, Labour are playing a seriously dangerous game by encouraging an ethical arms race, given the scale of their own misbehaviour. This will just look like hypocrisy (which is most-likely why they've hired a mouthpiece form outside parliament to do the dirty work. They really do think we are that stupid).
So, "flat-footed" and "desperate" are the words I would use to describe this latest move from the smearist wing of the Brownite-Mandelsonian tendency. Mexican stand-offs are usually fatal for all involved. I wonder whether someone in Labour has just pulled the trigger that ends-up, when the gunsmoke clears, with 500+ corpses of MPs' careers scattered around the village. I guess we'll just have to wait and see.
In the meantime at the very least someone with some kind of vision and nerve in the Labour party should tell Brown once and for all: this kind of crap doesn't work any more.