Michel Barnier ruthlessly exploited David Davis' weak spot while updating us on the Brexit negotiations

This is the bad-mouthing stage of the fight, when prize fighters insult each other at the weigh-in to try to intimidate each other. To be fair to Barnier, and although this is a bit 'school playground', David Davis did start it

Michel Barnier is a good negotiator. He knows his opposite number’s weak spot. So he went for it today, ruthlessly. “I am not going to comment on domestic politics in the UK,” he said, before going on to comment on domestic politics in the UK.

He did this indirectly, by saying, more than once, that he didn’t understand the UK’s position. After Theresa May’s Brexit war cabinet had met twice this week without agreement except to meet again at Chequers later, he was joining a vocal chorus of Remainer criticism that the UK Government doesn’t know what it wants.

That is not really true. The Prime Minister has been very clear about what she wants. What Barnier means is that the EU is not prepared to give it to her. Therefore, he says, it is up to her to come up with something else that the EU would let her have. “The time has come to make choices, and we await with great interest the choices,” he said.

And he has already said what the choices are. Either the UK must accept all the EU’s laws, or it can have nothing. The EU had generously agreed to a transition period, he implied – “It is the UK that asked for this period” – during which all EU law must apply. But if Theresa May, David Davis and the UK Government didn’t like it, then even that concession would be withdrawn.

This is the bad-mouthing stage of the fight, when prize fighters insult each other at the weigh-in to try to intimidate each other. To be fair to Barnier, and although this is a bit “school playground”, David Davis did start it. The Brexit Secretary’s outburst yesterday seemed designed to irritate the EU side: “I do not think it was in good faith to publish a document with frankly discourteous language and actually implying that they could arbitrarily terminate in effect the implementation period.”

Both sides are engaged in a negotiation, so you would expect them to set out the toughest version of their starting positions, but Davis’s language seemed quite pointlessly inflammatory. Contrary to his reputation, I am told that some of the officials who have worked closely with him respect him as a “a good 1950s-style politician”, not much into detail but good at making decisions.

Yet yesterday’s words seemed counter-productive. They allowed Barnier today to claim the high ground: “I’m not going to discuss David’s comment. It would not be useful. I’m not aggressive or vindictive and am not trying to punish anyone. I shall remain calm to the very end.”

Instead, he set out some of the most difficult problems that still have to be solved – such as the 750 international agreements on which third countries “will have their say” – and said: “Time is short.”

If this weren’t alarming enough, listen to what one member of the Brexit inner cabinet told James Forsyth of The Spectator: Brexit policy-making “looks worse from the inside than the outside”. Given how bad it looks from the outside, this is not reassuring.

On the other hand, it is possible that Barnier’s tough talk and May’s apparent indecision could be the prelude to compromise. It remains in the interests of both sides to do a deal, and many of the leaders of EU27 countries disagree with Barnier’s take-it-or-leave-it position.

Equally, May’s extended Cabinet discussions have given Boris Johnson and Michael Gove time to come up with their negotiating position and they still haven’t done so. Maybe Johnson will do it in his speech next week, but he is usually better at bluster than policy. In the end, May has a better chance of doing a deal than Johnson or Gove, and has broader support in the House of Commons.

Barnier’s hard line will also make any concessions that May is able to secure seem more significant. The more Barnier insisted that Britain must accept all the EU’s laws or be out in the cold, outside the single market and customs union, the more it seemed a third way could be found to keep Britain closely aligned with the single market.

But Barnier is right to say there isn’t much time to find it.