Brexit: Bercow chucks a hulking great spanner in the works

"He's breaking the constitution" - quite the accusation, laid at the door of John Bercow's grand speaker's apartments.

It's notable because it's the view of a government minister who is not one of those whose pulse quickens when discussing leaving or trying to stay in the European Union.

There is, of course, precedent in the very well-thumbed copies of Erskine May, the parliamentary rules, for the speaker's decision.

Quoting decisions as far back as 1604, John Bercow was quite clear that governments are not meant to be able to keep asking parliament the same question, in the hope of boring MPs into submission if they keep saying no.

But as another member of the government put it mildly, the speaker has a reputation for being "interventionist", and he has, this afternoon, chucked a hulking great spanner in the works.

The government seems to have been cooling all day on the idea of getting MPs to vote again on Theresa May's Brexit deal this week, for a whole shopping list of reasons.

But before Number 10 had a chance to make that decision, the speaker took it out of their hands.

There will be no "MV3", to use the terrible jargon - there won't be another vote on the prime minister's Brexit deal unless it changes.

Strangely, MPs who hate Theresa May's compromise, for different reasons, agree to an extent that it's the right call.

But there is anger and astonishment too, partly because MPs will have to explain another potential delay to the process, when many of them sense the public's desire is to crack on.

But there is festering concern about John Bercow's suspected wish to stop Brexit - always denied.

This time the speaker, whose job it is stand up for parliament, has - with no warning - made a decision that some in government believe veers too close to trying to block the government from what it seeks to do.

The way around it for Theresa May is far from clear.