When George Osborne appeared before the Treasury Select Committee this morning, he was left flummoxed by Labour MP John Mann, who asked him if he knew how much it costed to fill up a 1.6 litre Vauxhall Astra car.
"I'm not going to make an estimate," the Chancellor squirmed. "It's 20p a litre cheaper than it would have been if we stuck with your plans."
Mann wasn't placated by Osborne pointing out he had frozen fuel duty throughout his time in government, revealing that the cost of filling the 12.3 gallon Vauxhall Astra tank has risen under Osborne's chancellorship by £5 from £68.04p to £73.02p, blaming his decision to increase VAT from 17.5% to 20%.
Tory committee member Mark Garnier later asked the Chancellor a helpful question, allowing Osborne to explain: "Sadly I have no control over global oil prices".
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Mann has form asking Osborne surprising questions, having asked him last year when the last time was he ate a pasty. Mann's committee colleague Teresa Pearce recently forced Osborne to admit that he had never visited a food bank.
Osborne isn't the only politician to be sprung questions to see how "in touch" they are, with David Cameron surprising an interviewer who asked if knew the price of bread by praising his breadmaker.