EU leaders were explicit: the UK could have the extension it had asked for until January 31st as long as in the process it did not “undermine the regular functioning of the Union and its institutions”. And that it honoured its “obligation to suggest a candidate for appointment as a member of the European Commission” for that duration. A treaty obligation, at that.

Aware that failure to do so would cause legal problems for the new commission, due to take office on December 1st, British prime minister Boris Johnson nevertheless did nothing. And, after calling the general election, he announced that election “purdah” rules now prevented him from making any international appointments. An oversight, or bad faith? Now the commission has to take him to court to enforce the treaty.

The UK election, and a fear of being seen to interfere in it, may also be inhibiting EU officials and Irish ministers from publicly refuting Johnson fabrications. But the British prime minister’s recent mischaracterisation of his own withdrawal agreement’s provisions on Northern Ireland should also not go unanswered.

Ten days ago, Johnson, in a cynical effort to undermine DUP opposition to his new backstop, declared on a visit to Northern Ireland that its businesses would face no customs controls exporting goods to the rest of the UK. In effect, he was saying that customs controls on the Irish Sea, designed to obviate the need for border controls on the island, would be one-way only.

If firms were asked to submit forms, he said, contradicting his Brexit Secretary, they should "call me and I will direct them to throw that form in the bin … There will be no forms, no checks, no barriers of any kind”.

Unwilling to contradict the prime minister publicly, the commission nevertheless made clear that under the proposed deal “Northern Ireland will continue to apply the union’s customs code”, which includes mandatory pre-departure declarations and export formalities. These apply to goods produced in the North and those in transit through it from the Republic to the UK.

Tánaiste Simon Coveney insisted he was “not going to get into a debate with Prime Minister Johnson in the middle of an election campaign” but that “the deal is the deal” and “self-explanatory”.

Johnson’s comments matter. His attempt to minimise the effects of the proposed customs provisions may have the short-term desired effect of diluting opposition to the agreement, but, post-election, he has created a hostage to fortune.

When exposed as a lie, it is likely to fuel deeper resentment in the unionist community at British – and, specifically, Johnson’s – untrustworthiness, and make implementation all the more difficult.