It's like being a grown-up caught picking your nose and eating it. There you were all alone, absent-mindedly doing what you do – doesn't everyone? – when all of a sudden you realise that that door is open and someone's standing there watching you. Were they there when you . . . ? You drop your hand to your side and frown into your book, your keyboard, the clouds outside the window in the hope that either they weren't there, or that your new move obliterates, invisibilises, what you were doing. But for the rest of your life at any time, waking in the middle of the night, sitting on the loo, chairing a committee, that moment will come to you and you will seize up inside, curl, if it's at all possible, into a foetal hummock and moan gently. Can it be otherwise for the MPs who see their receipts in the Telegraph?