The EU-shaped divide at the heart of this Coalition
Only last Wednesday, the Prime Minister was squirming on the front bench as Ed Miliband taunted him for being weak on Europe. Today, David Cameron will be cheered by his own side as Labour taunts him for being strong on Europe.
The only man squirming on the front bench will be the Deputy Prime Minister, Nick Clegg. For Clegg has had to execute the most uncomfortable volte face.
On Friday, journalists were being briefed that he had been in constant touch with Cameron throughout the night and that he supported the veto. Now it transpires that he was fast asleep, discovered about the veto only as a fait accompli, and is "bitterly disappointed" by it.
"There's a lot of bad temper flying around," says one Lib Dem cabinet minister. "It was a big mistake." Clegg saw the horror in his own party and realised that he had to say what he really thought.
From now on, it looks as if on Europe, members of the Coalition will be allowed to disagree. As one senior Lib Dem puts it: "One of the great dividing lines in British politics now is between those who think the summit was a success and those who think it was a complete failure.
"From our point of view it was a shocking failure: a bad day for the Government, a bad day for Britain and a bad day for Europe."
That divide will be seen in the Commons today: Tories jumping up to congratulate the Prime Minister and Lib Dems expressing grave reservations.
Clegg's outburst yesterday was also designed to give breathing room to his Lib Dem cabinet colleagues. Nor is there any question of the Coalition breaking up. The Lib Dems are adamant that it was formed to deal with an economic crisis by no means over.
But how will two parties so fundamentally at odds be able to take decisions when new questions about the EU arise?
So far the technique has been, as far as possible, to avoid even talking about European policy.
The only time they touch on Europe in cabinet is when George Osborne gives a summary of the euro situation, after which Clegg always blames the Germans and Ken Clarke says it's a big mess.
Tomorrow's meeting will surely be different. Fresh from a Commons triumph, Cameron will be backed by all but Clarke.
And the Lib Dems themselves are divided on the nuances. Clegg agrees with Cameron that the City must be protected against more EU regulation. Cable thinks that Cameron is focusing too much on financial services when the Government is supposed to be rebalancing the economy.
Bizarrely, the best hope for resolving their Coalition differences is a collapse of the eurozone, though no minister dare say it out loud. They all suspect that even the fiscal compact agreed last week is unlikely to solve the eurozone's immediate problems. One politician compares it to two people coming across a man bleeding in the gutter and earnestly discussing where to build a hospital. Markets will decide whether the eurozone survives long before any new fiscal rules.
And if the euro doesn't endure in its present form, euro-enthusiasts will have to rethink fundamentally their view of Britain's relationship with Europe.
Instead of their reflex assumption that Britain suffers from being "isolated", they might start to appreciate the security, flexibility and independence we have gained from staying out of this dangerously ill-conceived project.
If a herd is hurtling towards a cliff, after all, the one who peels away saves his life.
Even the Lib Dems recognise this. They don't want the euro to collapse, but if it does, at least they will no longer be clamouring for us to be at the heart of Europe. And the British exercise of the veto, which so embarrassed them, will be completely overshadowed.