About last night...

"The Commons has decided it wants this country to be Belgium," snarled a senior minister this morning.

He blamed a burgeoning "little Englandism," that wants the outside world to go away, the mindset, he added witheringly, behind UKIP. In the backwash of Thursday's surprise Government defeat, I tweeted that this was an important constitutional moment, and no PM could now commit British troops without Commons consent. I don't retreat from that the morning after the night before.

The Commons has just taken a big bite out of prime ministerial powers under the so-called Royal Prerogative. Previous PMs have enjoyed wide powers to deploy troops and authorise armed force, in the expectation that their Commons majority would, if asked, approve their actions after the event.

That began to crumble a bit during the build-up to the Iraq invasion, when Tony Blair promised a Commons vote on British participation, and with the aid of an intensive whipping operation, won the consent he needed. What has changed now is that, quite unexpectedly, a Prime Minister has failed to get that consent. There's some scholarly debate about when this last happened, but more than a century has elapsed since anything comparable has occurred. And the reason it has happened now is that the Commons has developed a will of its own. But let's just step back and restate what has just happened; a Prime Minister has been unable to get his recommendation for the use of armed force through Parliament.

The whole incident reopened the issue of parliamentary approval - this is one of those grey areas which crop up around the blurred borders between Government and Parliament. There are reports from assorted select committees, the Public Administration Committee under the saintly Tony Wright, The Lord Constitution Committee and, most recently the Political and Constitutional Reform Committee calling for the rules around the approval of armed force to be clarified. The PCRC called for the Government to produce a memorandum setting out its understanding of the existing rules, a request it may well repeat, given that the issue has been festering at least since Iraq.

Thursday's debates had a real sense of Deja Blair about them... There was a contribution from Iraq era foreign secretary Jack Straw bemoaning what he called the egregious intelligence failure over Iraq, which brought a rapid rebuttal from Tory Richard Bacon, who said the Blair Government had exaggerated the intelligence... More than one MP inadvertently said Saddam, when they meant Assad, and in the end the Commons gave David Cameron the thrashing it never administered to Tony Blair.

Who's to blame? Some fingers are being pointed at Nick Clegg's winding up speech. He was certainly given a rough ride, but then he always is... Maybe he is the wrong man to convince wavering Tory backbenchers, but there were wavering Lib Dems to reel in too. What about the Chief Whip, Sir George Young? Perhaps the Government whips were lulled into a false sense of security by the easy defeat of the Labour amendment to the Government motion... and it is certainly embarrassing that several ministers missed the vote. But I don't think the whips should be blamed for failing to rescue David Cameron from the mess he had got himself into. Recalling Parliament, then having to water down his motion, then discovering he had seriously underestimated the disquiet on the Government backbenches. The whips can't make euro sceptic MPs into unquestioning Government loyalists, or turn HS2 opponents into enthusiasts. And they can't make Iraq-scarred sceptics into obedient military interventionists either.

So what does the vote mean? One thing it doesn't mean is that Britain would not be able to shoot back at an invader till the Commons had voted; all kinds of contingencies will remain at the discretion of the PM, including immediate defence against a threat to the country or its interests. But in cases like Syria, the Commons is no longer a rubber stamp. Prime Ministers will need to secure consent - and it may not be forthcoming.

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