Brexit: Something has changed but is it enough?

"Devastating" - that's how one influential Brexiteer described the attorney general's legal advice.

Yes, the Brexiteer lawyer Geoffrey Cox says the negotiations with the EU and tweaks to the deal have reduced the risk of the UK being stuck in the controversial backstop for ever and a day.

That's why last night, Theresa May and Jean-Claude Juncker looked so thrilled and delighted to have managed to broker something.

But what Mr Cox also says clearly is that the risk still exists.

Without going through the minutiae of the three-page legal opinion, in short, he has given the prime minister a fig leaf to try to patch a gaping political hole, rather than a generous cover with room to spare.

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It is not true to say that "nothing has changed". And remember the latest round of negotiations were never going to tear up the whole deal on the backstop, or change it fundamentally.

However, political expectations had been stirred - the last few days have always been about making changes at the margins that would make the UK feel better about the whole thing, not make it go away.

And there will be some Tory MPs who use this moment to do what they have wanted to find a way to do for some time - change their mind, and walk through the Aye lobby tonight to back the prime minister.

One is said to have joked to the prime minister they'd wanted her to "bring a rabbit out of the hat from Brussels, and you've come back with a hamster, but that's good enough for me".

But as things stand the number of switchers seems far less than required to avoid another defeat for the prime minister. Last time out she was beaten by a record 230 votes.

One cabinet minister guessed the number tonight might be around 150. Everyone is guessing still.

But this looks like another dreadful day for Number 10, and another moment when doubts will be on display about not just the divorce deal with the EU, but about the prime minister's leadership too.

Something has changed yes, but not enough.