I know Harriet Harman is not supposed to be taken seriously, so I’m prepared to believe that she just struggles with numbers and didn’t knowingly mislead MPs today. But it’s worth correcting the record on one crucial point. “We have paid down debt,” she says. Actually, if you take the last Budget into account – it ranges to 2013/14 – decisions taken by her government will have increased national debt by more than every government since the Norman Conquest. Put together. If this is her definition of paying down debt, I’d hate to see her overdraft. Don’t they teach them anything in St Paul’s?