There was shock and dismay in Brussels at the news of a breakdown in the Brexit talks after Dominic Raab’s unexpected visit on Sunday had raised hopes that a deal could be reached.

The UK Brexit secretary arrived for unscheduled talks with EU chief negotiator Michel Barnier in the afternoon. Later, EU ambassadors were summoned to a meeting that one report had suggested was to get early sight of a deal.

It was not to be. Raab was over not to give a final political impulse to a deal that was close to signing, but to say that it would not happen. That London could not stomach the compromises necessary for the Irish backstop agreement.

Diplomatic sources in Brussels stressed that they believed, however, that the talks would resume after the summit this week ahead of a tentative summit in November that is still expected to go ahead.

With the crunch summit looming on Wednesday and “sherpas” due to arrive in town on Monday to prepare it, time had run out if the “decisive progress” required at the summit was to be achieved. The meeting of sherpas, prime ministerial aides who prepare the summit, has been cancelled.

Mr Raab, who stayed for less than two hours, refused to meet journalists in Brussels, but officials said that “with several big issues still to resolve, including the Northern Ireland backstop, it was jointly agreed that face-to-face talks were necessary ahead of this week’s October European Council”. The suggestion appeared to be that a deal was within reach.

One of the outstanding issues, upon which many believed the deal could have foundered, hinged on ways of time-limiting the backstop guarantees that the EU requires to sustain a frictionless border in Ireland. The UK fears that difficulties down the road in reaching an agreement on the future relationship between the EU and UK could see it indefinitely committed to remaining part of a customs union.

That is particularly so if the EU and the Republic insist that the backstop guarantee must remain in place if such a comprehensive agreement does not provide the level of safeguards needed to secure that frictionless border. In practice, many say that would require continued customs union and single market membership by the UK.

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Other thorny outstanding issues include questions about the governance of the Withdrawal Agreement, specifically the standing of the EU court, and problems relating to post-Brexit mutual recognition of “geographical indicators”, the exclusive designation of products by their origins – from Scotch whisky to Cheddar or feta cheeses.

The week’s EU agenda remains crowded by what could be termed collectively a “dolomite” of six distinct EU summits, in addition to preparatory meetings:

Prior to Sunday’s events, “sherpas” were due in town on Monday to get Mr Barnier’s state-of-play report and give an initial assessment of their leaders’ likely reactions to the Brexit deal and other summit topics.

In Luxembourg foreign ministers will lay the basis for any foreign policy resolutions. On Tuesday, the European Commission will meet Mr Barnier to hear his report on the failure, and he will almost certainly meet the MEPs’ working group on Brexit.

The General Affairs Council also meets in Luxembourg on Tuesday in two formats. The initial meeting will also discuss preparations for the European Council, the vexed rule-of-law disputes with Poland and Hungary, and the next multi-annual budget. Then European affairs ministers of the 27 other EU states will meet in Article 50 Brexit format to get their Barnier report.

On Wednesday, the dolomite opens with a “tripartite social partnership summit” when representatives of business, unions and civil society meet commission and council presidents, Jean-Claude Juncker and Donald Tusk.

That evening the 27 other member states meet for a Brexit-themed dinner, the European Council in Article 50 format. British prime minister Theresa May had been invited to address them for 10 minutes, and then to leave ahead of their deliberations. Whether she will do so now is unclear.

In the absence of “decisive progress” towards an acceptable Brexit agreement they will now not agree to convene a summit in mid-November to confirm the legal text of a Withdrawal Agreement. They may decide, however, according to one report to use the tentative summit to discuss preparations for a no-deal and the likely departure of the UK at the end of March without a transition period.

On Wednesday, the leaders were also to get sight of an outline political declaration on the future framework of EU-UK relations. That now appears unlikely.

On Thursday morning, the 28 leaders will meet the president of the European Parliament for the opening of the European Council proper and discussions on internal security, migration, and a number of “conclusions” on foreign policy.

Over lunch they convene for an expanded informal “Euro Council” (19 euro members and eight aspirants to membership) to discuss the state of play of negotiations on the deepening of the Economic and Monetary Union with a view to agreement on legislation at the European Council summit in December.

On Thursday evening, they all sit down to dinner with the leaders of the 21 Asian states in town for Friday’s Asia Europe Meeting (summit) which is followed in the afternoon by an EU-Republic of Korea Summit.

The dolomite is expected to conclude at half past four on Friday evening.