Theresa May’s Salzburg speech shows she is inching towards a compromise on the Irish border

That is why May’s upcoming meeting with Leo Varadkar, the Irish prime minister, could be important

The prime minister was allowed 10 minutes to make her pitch for compromise to her fellow EU leaders on Wednesday night as they had their after-dinner coffee. She repeated what they already know, which is that the European Commission’s plan to keep Northern Ireland, but not the rest of the UK, in the EU customs zone was unacceptable to her.

“That I should assent for a legal separation of the United Kingdom into two customs territories is not credible,” she said.

That speech was a formality. The real business will have been done in the private chats, between prime ministers and between their officials, around and away from the dining table under modernist chandeliers.

The symbolism of the setting for the dinner was weird. It looked like a meeting of Sith lords to discuss the fate of the Rebel Alliance, and was held in the theatre where the Von Trapp family sang their last concert before fleeing. Theresa May’s speaking slot, with no discussion allowed because that would cut across Michel Barnier’s brief as chief EU negotiator, seemed like quite a calibrated insult to Britain.

However, May just keeps ploughing on, making her case. As our Europe correspondent reported last night, there are signs of possible compromise on both sides on the Irish border question, which is the most difficult of the remaining problems.

There are hard practical questions to be decided, but there is also a lot that can be done by constructive ambiguity of language. A lot depends on how both sides define a “hard border”, or a “border down the Irish Sea”, or “regulatory alignment” or even “a customs union”.

That is why May’s meeting with Leo Varadkar, the Irish prime minister, later on Thursday, could be important. As important as the unofficial signals that she could be picking up from other EU leaders about where they think the scope for compromise might be and how worried they are about the prospect of the two sides failing to agree.

What is less important is what the EU leaders say in public today in their various media appearances. We have already had Joseph Muscat, prime minister of Malta, and Andrej Babis, his Czech counterpart, on the radio urging the British people to change their minds about leaving.

Like May’s 10-minute speech, these sentiments are not new.

All the other EU leaders have said from the start that if the UK changed its mind they would be happy to allow us to do so – and for us to remain EU members on current terms. But it does add to pressure on May to reach a deal, because whatever she says about the choice facing the British parliament in the end – her deal versus a no-deal Brexit – she knows that there is always a third possibility: that a deadlocked parliament might opt to postpone Brexit, and even to hold a referendum to try to reverse it.