Hints that the ground may be shifting, albeit incrementally, in the Brexit negotiations were given by EU negotiators on Monday when a key European Commission discussion ahead of next week’s EU summit was postponed.

A paper outlining the basis of a joint declaration on the future EU-UK relationship was pulled from Wednesday’s meeting by EU chief negotiator Michel Barnier.

Sources suggested that Mr Barnier was keen to reflect an evolving UK position on the customs union and the Irish backstop in the paper, an amended version of which will now reportedly go first on Friday night to the prime ministers’ “sherpas” – senior aides who prepare the summit.

The paper is expected to be the basis of an annotated joint political declaration between the 27 and the UK on the post-Brexit future relationship between the EU and UK. This will accompany the Withdrawal Agreement treaty and set out a limited range of options for a free trade agreement that respects the integrity of the single market and the outlines of an agreement on internal and external security.

New written British proposals on the backstop, which is a protocol to the Withdrawal Agreement, are expected any day.

They are likely to propose, sources in London suggest, that the Border issue be resolved through a combination of the temporary all-UK continued membership of a customs union, and continued Northern Ireland regulatory alignment with the EU. Such alignment would be ensured through sanitary and phytosanitary checks in the Irish Sea and market-based checks on goods.

Replaced

Unlike initial UK proposals, the backstop is not likely to be time-limited but will be replaced if and when a comprehensive future relationship deal is agreed.

The commission is expected to test the water on the evolving proposals with the leader of the DUP Arlene Foster and UUP MEP Jim Nicholson when Mr Barnier meets them here on Tuesday morning. They will give a press conference afterwards.

Brexit secretary Dominic Raab is scheduled in Brussels on Thursday or Friday for further talks.

Following the meeting of sherpas, ministers will come to Luxembourg on Tuesday next for final preparations for the summit, which begins on Wednesday with a Brexit dinner of the 27 remaining states. British prime minister Theresa May will address them briefly beforehand before withdrawing from the meeting.

A brief moment of levity was injected into proceedings on Monday when commission president Jean Claude Juncker opened a speech in Brussels with the briefest musical shimmy that poked fun at Ms May’s Abba tribute at the Tory party conference. Strictly diplomacy.