Donald Macintyre's Sketch: Know your Ford Focus from a Vauxhall Astra, Mr Osborne? Sadly, that was not quite George Osborne's approach. Labour's John Mann asked him, several times: "How much more does it cost to fill up a Vauxhall Astra from the moment you became Chancellor till today?" Osborne hadn't known, of course, the cost of a full Astra tank, or by how much it had risen. And no doubt there's a case for politicians learning the price of selected homely goods, so that they can say: "Well, I'm not sure offhand about the Astra, but I can tell you that a tank of petrol for the Ford Focus, also in the compact range, costs around £83." But then it wouldn't be any better if he did know, since then he would have to admit that, as Mann eventually, and portentously, announced, it had gone up by £5. So Osborne was sensible to answer: "Well, it's about 20 pence per litre cheaper... than if I'd stuck with the Budget increases you voted for." And repeat it as often as Mann asked him the question. Which was pretty often. Tory Mark Garnier then asked a classic patsy question: "How much control do you as an individual have over global commodity prices, in particular energy prices? " Er... None. Garnier is surely intelligent enough to know not to get this sycophantic unless your man really needs rescuing. More telling was the Tory chairman Andrew Tyrie's suggestion that the multibillion-pound Help to Buy election bribe - as he tactfully didn't call it - was pouring "vodka into the punch bowl just as the party gets going" by creating a housing bubble. Tyrie asked how Osborne was going to end it after the election, when it might be all too popular. Osborne said that the Bank of England had a "lock" which would stop its extension beyond three years - even though the Bank's governor recently said it hadn't. Labour's Pat McFadden extracted a confession from the Chancellor that the Exchequer gains from selling the student loan book didn't actually take account of future lost revenue in loan repayments. And a promise -or threat - that he could protect government departments while shrinking deficit by cutting "many billions" more in welfare. Either this means serious pain after 2015. Or the figures don't add up. Or both.