Westminster woke up on Tuesday to find that a promise to ensure the continuation of regulatory alignment between the two parts of Ireland had expanded to include the entire UK.

Brexit secretary David Davis stood at the despatch box in the House of Commons and asserted without a blush that this had been his government’s intention all the time. “The presumption of the discussion was that everything we talked about applied to the whole United Kingdom. ”

Davis cited Theresa May’s Florence speech, in which she said Britain may wish to stay closer to the EU on some issues than others after Brexit. She said that there were areas in which Britain would want to achieve the same outcomes as the EU, but by different regulatory methods.

“We want to maintain safety, food standards, animal welfare and employment rights, but we do not have to do that by exactly the same mechanism as everybody else. That is what regulatory alignment means,” he said.

Although Labour denounced the shambolic nature of the Conservative government’s handling of the Brexit negotiations, all parties agreed that any regulatory alignment should be UK-wide and nobody spoke in favour of any special regime for Northern Ireland.

Opposition MPs blamed the prime minister for the shambles in Brussels, and some suggested that she was too much in thrall to the DUP’s 10 MPs.

The DUP’s leader at Westminster, Nigel Dodds, was in no doubt about where the blame for the fiasco lay – at the door of the Government in Dublin.

Damage

“It should come as no surprise that Dublin and the Irish Government wish to advance their interests. The aggressive and anti-unionist way in which they have gone about doing so is disgraceful. It has set back Anglo-Irish relations and damaged the relationships built up within Northern Ireland in relation to the devolution settlement. That damage will take a long time to repair.”

Only a handful of other MPs echoed those sentiments in the chamber. Privately, however, MPs and officials in London are puzzled by the way Leo Varadkar and Simon Coveney handled Monday’s events.

Coveney’s premature victory lap on Morning Ireland appeared to raise the DUP’s hackles, as they concluded that anything which could bring such joy to Dublin must be a snare and a deception.

The Taoiseach’s press conference after the failure of the talks in Brussels came across as undiplomatic. And his assertion that regulatory alignment and no regulatory divergence were the same thing was not only inaccurate but unlikely to help May to climb down from the tree she had been chased up by the DUP.