Boris Johnson has this lunchtime rejected the claims contained in a new leaked Treasury analysis of the impact on Northern Ireland of his new Brexit deal.
In characteristic Mr Johnson style, he also admitted he hasn't read it.
Notwithstanding those two things, the new leak of an internal government presentation from Labour may be the most significant document to enter the public domain during this campaign, and perhaps the most important leak since "Yellowhammer" no deal planning documents - even if it does not change a single result in next week's election.
The most controversial element of the prime minister's revised Brexit deal, struck in mid-October, relates to Northern Ireland. This leaves Ulster tied closer to the rest of the European Union than the rest of the United Kingdom.
However, the exact nature of those ties - and the consequences both for citizens and businesses in Northern Ireland that flow from them - have been shrouded in mystery and confusion.
The uncertainty revolves around two big questions. Firstly, does the deal weaken the bonds of the United Kingdom in such a way that could fracture the union. Secondly, does the revised Brexit deal have negative economic consequences for Northern Ireland.
Today a new leaked Treasury analysis suggests that the civil service answer to both of those questions is - unambiguously - yes.
The 15-page leaked document, entitled "NI Protocol: Unfettered access to the UKIM" (internal market), contains one bombshell and pages of damning analysis.
It reveals for the first time that not only will there be customs declarations on goods going from Northern Ireland to Great Britain - something that Brexit Secretary Steve Barclay confirmed but Boris Johnson denies - but also there may be checks for goods going in the other direction, from the British mainland to Northern Ireland. This is a further new significant border in the Irish Sea which the DUP will recoil from.
The impact on the Northern Ireland economy could be devastating, this suggests. It claims 98% of Northern Ireland export businesses are "likely to struggle to bear this cost" of customs declarations and documentary and physical checks on goods going within the United Kingdom.
This will hurt citizens, it says. High Street prices are likely to rise, as is unemployment in the retail sector. The additional burden for Northern Ireland business is the financial equivalent to increasing tariffs of 30%.
The Treasury document is damning on the impact on the fabric of the Union. It says it means that Northern Ireland is separated "in practice from whole swathes of the UK's internal market" and this means the "economic union" is "undermined".
In a move likely to be noted in Scotland, where the SNP are on course to take more seats in this election and renew their push for independence, it adds the different arrangements will mean a "precedent set for the different treatment for constituent parts of the United Kingdom".
The people of Great Britain rarely seem to vote on Northern Irish matters. The fact that Northern Ireland has not had a functioning devolved administration for over two years has barely featured in the British conversation about the election, even if it rightly dominates in Belfast.
They have separate political parties, meaning that Westminster politicians feel little electoral pressure about what happens in our own country on the other side of the Irish Sea. So however significant the documents today are, it may well not change many votes in next week's general election.