A weekend is a long time in politics.

When it comes to life under Gordon Brown, it’s often a case of ‘think of a number’. So it was that the PM was once more caught out thinking of numbers and then doubling them last week. His 300,000 businesses helped out by government turned out to be just the 158,000 – which was a good recovery given that only ten minutes earlier he’d accepted that his Chilcot evidence about £18 billion of investment in Iraq & Afghanistan was also invented.

Stephen Byers thought of a number and decided it was between three and five thousand pounds. Patricia Hewitt decided that she wasn’t “a sort of cab for hire” like Stephen, but was nevertheless happy to whore at a similar daily rate. It says a lot about Byers that he obviously thought his excuse (‘I’m an exaggerating fantasist’) would absolve him of blame. But Top-Spin of the weekend goes without question to Number Ten’s press office, which offered a cute variation on the mental health slur as an excuse for Margaret Moran’s decision to join the Three Grand Tour: “I think everyone accepts that Margaret has not been well of late”. Bless.

Such is the ubiquity of criminality among New Labour’s elite, Liam Byrne assumed that his driver must be part of the firm, and so wound up accusing the poor bloke of nicking his wallet. The chauffeur up and resigned on the spot, but thus far the most likely explanation seems to be that Treasury expert Byrne left his wallet at home; Royalty does, after all, pride itself on never carrying money. Liam’s memory lapse makes a welcome change from senior bods leaving NATO battle plans on the 5.34 from Waterloo: and it’s good to see that his analysis of the likely causes of insolvency remains as measured as ever.

If The Observer, Independent and New Statesman are to be believed, Vince Cable is a shoe-in for Chancellor. You can imagine Nick Clegg’s shock on waking up this morning to discover this – especially as only a fortnight ago, the Liberal Democrats’ leader told us he would not take part in any formal coalition. Tonight there will be worse news for Nick, as his wife is about to tell the nation she has no intention of taking part in any silly elections, preferring her children and career. She sounds to me like the sort of wife every man should want.

But Nick has powerful allies, for Harry Potter is to be one of his supporters. The young actor confirmed today that he will campaign ‘actively’ for the Libdems, selling them hard to the younger voter. Harry’s access to broomsticks must be a great relief to hard-pressed Party treasurers increasingly worried about travel bills mounting up before the election has even started.

I say it hasn’t started, but everyone knows Election Day is May 6th. Equally, we all know the details of Darling’s Budget, because most of the important bits have been leaked. It is a feature of political life these days that everyone with a pc and access to the internet knows what will happen before the audience. For example, if you ring the Business Ministry press office after 9.30 am, they will foretell the future of Lord Mandelson’s less than mysterious movements on that day, and happily send full details of every speech he will deliver.

On a similar basis, diligent correspondents discovered this morning that Ed Balls wants to introduce regular tests to discern whether teachers are still fit to teach, or whether they might (in the previous three years) have succumbed to the insane desire to vote Conservative…even perhaps to teach kids something they will find useful after leaving school. If only there was the remotest chance that politicians would submit to a similar test.