HOW on earth to explain Vince Cable's extraordinary comments about Rupert Murdoch's takeover of BSkyB to two undercover reporters?
After all Mr Cable is a very intelligent man – at least if you believe his own publicity – and he was speaking about a very sensitive matter over which he has semi-judicial authority to people he had never met before.
On the face of it, his eagerness to blab without any restraint is so bizarre as to be entirely inexplicable.
But in fact the explanation is a very simple one.
It is precisely the same reason why the Business Secretary was so easily seduced into making a fool of himself in a Christmas special of the BBC's Strictly Come Dancing.
And it can be summed up in a single word – vanity.
You can imagine the scene when two attractive young "constituents" are so fascinated by Cable's political career that they ask him his views on the coalition Government.
Now, Cable clearly enjoys the trappings of power – the limousines, the red boxes the chance to make decisions that matter, the right for the first time in his life to be taken seriously.
But he also does not want these giggling young ladies to think he is a mere government lackey. He wants them to know than in his breast beats the heart of a true radical!
So he puffs out his chest and boasts he could bring down the Government by quitting, which he calls the 'nuclear option', and that he has declared war on Murdoch adding "I think we are going to win".
Well, not now you're not.
How utterly pathetic!
But Cable's behaviour neatly sums up the dilemma faced by all Liberal Democrats.
They seem unable to decide whether they want to be proper, serious politicians making tough decisions that may prove unpopular, or instead to court easy popularity by backing wildly unrealistic and irresponsible policies – as they have always done in the past.
It is a choice between mature politics and empty posturing – and the Lib Dems have to understand that they can't do both.
We've seen Cable wrestling with the problem before. For a while he couldn't even decide whether to back the tuition fee increases that he himself had proposed.
And of course his boss, Deputy Prime Minister Nick Clegg, suffered a serious attack of the wobbles just because a few posh anarchists desecrated the Cenotaph.
Time to "man up" fellers.
No-one said being in government was going to be easy. You simply have to decide if it is a job you really want to do – and if you are big enough and brave enough to do it.
I feel 2011 will be the year the Lib Dems have to decide to either grow up or ship out.
The leaker leaked
I nearly choked on my toast the other morning when Wikileaks founder Julian Assange complained on BBC Radio 4 that details of the sex assault allegations made against him by two Swedish women had been made public.
"The Swedish prosecution has been, deliberately and illegally, selectively taking bits of its material and giving them to newspapers," he protested.
In other words, the world's leaker in chief was objecting to information being, well, leaked!
The exchange was a perfect illustration as to why total transparency is not always desirable. Some allegations, such as the ones faced by Assange, are so serious that they should be properly tested in a court of law.
That's why he should return to Sweden to see justice done.
Later in the interview, he was happy to be compared to a martyr and a messiah.
In the narcissism stakes, I think US President Barack Obama may well have just about met his match.
Season to be cheerful
The weather is lovely to look at, but horrible to travel in. Time to pull up the drawbridge, forget politics for a while, pour yourself a large drink and enjoy the company of friends and family. Happy Christmas to you all.