How can MPs insist that they have “done nothing wrong” — and then hand back the money they’ve claimed? How can they return these expenses as if admitting guilt, yet fail to resign and let the voters pass sentence? It started with Hazel Blears waving her cheque yet declaring her innocence; and with David Cameron demanding that his MPs forfeit even allowable expenses if they looked bad. The reasoning seems tangled.

There is a key to understanding it; but you will never get the logic of the MPs’ responses to the expenses crisis until you know their secret starting-point. In their hearts they do not believe most of them have done anything seriously wrong. So it’s a gesture, not an admission.

They are furious (and genuinely shocked) at the crooks in their ranks: the small minority who have acted with such dishonesty. They bitterly resent the greed of a larger minority whose claims (such as for poppy wreaths or luxury Jacuzzis) have been outrageous.

But for more than a decade they been told that, up to a certain level, an MP could claim the costs of running a second home but must submit receipts. As the total costs of running a second home do usually exceed that maximum, they’ve started with the bottom line then assembled receipts more or less randomly until they get close to it, never thinking how trivial, undignified or greedy the montage of DVD players, kennels, fancy wallpaper and feather dusters would look when spread across the newspapers in an itemised list.

We can with rough justice divide our MPs into wolves, pigs, sheep and lambs. About two thirds of them are, like most of their constituents and most of the media, sheep. The lambs, a tiny minority, are as pure as pure, even if their sanctimonious bleats sometimes grate. The wolves, the other tiny minority, are out-and-out fraudsters, and quite possibly criminals. The pigs have broken no laws but behaved with disgusting greed.

But the sheep — about two thirds of the House — have simply grazed where the others grazed, keeping within the fenced perimeter of allowable expenses, finding safety in numbers and never asking if the boundaries were right, or how it might look in the press.

Now the sheep are scared and lost. Still bewildered at the sound of a nation baying for blood, and noticing some of the other sheep apologising and handing money back, everyone’s started doing it. The aim is to make the world go away for a bit, after which they hope everything will calm down and the electorate will be more receptive to their explanations.

And — spit it out, Parris — I feel some sympathy for them. When I was an MP it was not permissible to claim much more than your mortgage or rent. Like most, I claimed my mortgage, building up (and this is the eyebrow-raiser that critics almost overlook, and the really substantial drain on the public purse) a substantial capital asset at the taxpayers’ expense.

I paid for cleaning and decoration out of my own pocket, but had it been the case then that an MP could claim for these, would I have done so? The answer has to be yes. I’d have been one of the sheep.

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