One of the perks of being Prime Minister is when you address the House of Commons you always have your back to your own side, providing the perfect answer to those who say you can only tell the truth when it stares you in the eye.
Thus in theory only Her Majesty’s Loyal Opposition is really able to see just how shifty you are – unless of course you speak.
And this was the mistake that David Cameron made, not for the first time, as he turned up in the chamber to answer charges of confusion and obfuscation over his position on Europe and referenda.
If there is one thing that those members of the Tory Party, who need written permission from their doctors to be out on the streets, hate even more than the Lib-Dems and John Bercow it is Europe – or at least those bits that don’t involve skiing and the French Riviera.
So extra pills were ordered and taken when they heard this weekend that Dave had at last said he was in favour of a referendum.
His conversion bore no relation of course to the plan by former Defence Secretary Liam Fox, who qualifies in both the doctors’ and recidivist camps to trundle out his referendum guns today.
But as befits a Tory Party in chaos ever since Chancellor George produced the budget-from-hell, more chaos was just around the corner.
Even as the faithful were reading the good news in their Sunday papers Foreign Secretary William Hague was being trundled out himself to say Dave had not meant it.
And so the scene was set for the perfect appearance by Dave in front of a less than happy government party and a delighted opposition.
Missing in action yet again was the back end of the coalition horse, deputy Prime Minister Nick Clegg, who has taken to displaying his increasing contempt at being treated increasingly with contempt by not turning up.
Earlier he had made it clear that once again unwarned about Dave’s latest attempt for party popularity, he believed the issue (if not himself) irrelevant at the moment.
And so it was a Nick-less Dave who stood to clear the confusion and announced that this was no time for a referendum.
Just to make it quite clear there might be a time – some other time but not this time – and then he moved on to the bankers.
An hour of excruciation followed as Dave equivocated his way through the minefield of his own members egged on by Labour, delighted at another afternoon of car-crash politics.
Ed Miliband had kicked off the sport by accusing the PM of a long-standing position on renegotiation; long standing because it’s not getting anywhere.
Dave sweated on, his head looking increasingly big for his hair, as Tory after Tory asked him the one question he could not answer: when?
He had planned to escape after an hour when George would take his place in the dock over Barclays but that took no account of the master of ceremonies at the event, Speaker Bercow.
He mercilessly let the session run an extra 25 minutes. And it’s PMQs again on Wednesday.