What's the big picture behind Brexit 'backstop' drama?

What just happened?

Brexit was always going to be difficult, it's complicated.

The Tory party doesn't agree with itself, the government is split and Brussels is not looking to give us an easy ride.

The Brexit secretary claimed a victory, but in Westminster what starts out as a "win" can, by morning, seem like a hollow victory.

And tonight, senior figures in government are questioning whether David Davis really achieved very much.

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He may have saved face after making a huge fuss but look carefully at the concession he won, they say, and it doesn't really mean very much.

A few words here, a loosening up of the planned language there, perhaps the victory really was Theresa May's?

Did she pull a fast one on him, making him believe he had pulled off a huge win, when in fact, he walked away with only a few crumbs?

Hold on.

Whatever words were agreed, whatever substance was changed - and indeed, the alterations are not substantial - let's look at the big picture.

The prime minister was blocked from forging ahead with her hoped-for plan because one of her ministers stopped her in her tracks.

The disagreement played out extremely publicly, and in the end, she chose to budge, rather than risk a resignation that could have shaken the government to the core.

Perhaps David Davis's credibility has taken a knock. A resignation threat that isn't acted on dulls the potency of the (potential) next one.

But some Brexiteers are convinced that today's shenanigans show that when they really push Theresa May, they can move her, even though over many months they have accepted the grinding inevitability of compromise.

That is not what happens when prime ministers are 100% in charge.

That is not what happens when an administration is firing on all cylinders, when it is driving the agenda, and creating forward momentum.

And for her rivals and internal critics, of whom there are plenty, Theresa May seems tonight just that bit easier to push around.

Then, just when things might have seemed to be calming down, a recording of the foreign secretary's own views on Brexit was leaked to the news site Buzzfeed, where he was heard, urging the prime minister to show more guts, warning there could be a Brexit "meltdown".

It's not surprising that he holds those views, nor indeed that they made their way into the ether.

But frankly, it's not just guts that Theresa May needs, but all the help she can get.

And if the last 24 hours are anything to go by, that help is not coming from all of her colleagues.