The TUC Blog catches John Rentoul imagining that everyone in Britain is rich enough that they have to do a tax return. Ah, the sweet smell of entitlement. Of course, the substantive point here is that the planned child benefit cut, now disintegrating all over the scope, will require tax return filers to tick a box. But the majority of taxpayers are on PAYE. And that will need them all to be given a new tax code.

OK, so add “recode the entire working population” to the to-do list. But we’d like to reassure the public that David Cameron, however, is a Very Serious Person. There is nothing at all about him that would suggest that he’s not the man to tackle this gigantic administrative challenge. Any rumours to the effect that he resembles Fotherington-Tomas, is uterly wet and a weed, or thinks Tim Nicebutdim is a bloody good bloke, are foul fabrications put about by those who would discredit him.

Let’s roll the tape.

"I don't start from the proposition that we are all appalling cheats and liars and tax evaders, and the rest of it, and I am quite sure this change will secure the very generous revenues that the Office for Budget Responsibility have pencilled in. So I don't predict a problem.

I’m not sure which is funnier - the bumptiousness, the rosy cheeks, or the “very generous revenues”. The sum “pencilled in” is a massive £2.5 billion, or some 0.37% of government expenditure, and Dave’s already spent £1bn of that on the tax credit for smug marrieds (remember them?) he chucked at the Tory conference as a sop. That’s before the bill for pulling and reissuing everyone’s PAYE tax coding notice comes in.