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Evan Davis offered David Cameron an inch on Monday night and the prime minister gladly took a mile, telling Newsnight’s newly installed grand inquisitor that he would love to see the imperial system for weights and measures restored to prominence in British schools.

While most of us change with the weather between old and new systems — when it’s freezing, it’s 0C, when it’s hot, it’s 100 degrees in the shade — parliament seems tied to old-school ways: defending his corner at PMQs, Cameron will insist that there was “not one ounce of complacency”; responding in kind, Ed Miliband declaims: “A few inches of glass... separates the public in the gallery from the House of Commons but there’s a gulf miles wide between the