Voters in the Derry constituency of Foyle are preparing to choose, on Thursday, their new MP. A solidly nationalist seat, the winner is predicted to come from one of the two large nationalist parties, incumbent MP Elisha McCallion for Sinn Fein, and the leader of the SDLP, Colum Eastwood. Peadar Toibin’s Aontu is running councillor Dr. Anne McCloskey, and while her campaign will be fascinating to watch in terms of its impact on Sinn Fein, she is not expected to contend for the seat.

As election day approaches, and tensions rise, voters across the constituency received a very strange letter in recent days, purporting to be from the SDLP candidate, Mr. Eastwood:

It would be very strange for a candidate to ask every voter for €1,000 in the last days of a campaign. Indeed, it’s the kind of thing that could put people right off. The only problem is that the SDLP and Mr. Eastwood insist that they did not send this letter:

“I am disgusted that fake letters purporting to be from me have been delivered to houses in Derry. Let me be clear, these letters are not from me nor are they from anyone associated with my campaign. This is an organised attempt to lie to the people of Derry, to poison our democratic process and those responsible should be ashamed. The people of Foyle know that this is a close race between myself and Elisha McCallion. Voters should make up their minds on our records, not a campaign of dirty tricks.

Sinn Féin has called us dishonest – they must now condemn these vicious lies.”

Who could possibly benefit, in a two-horse race, from the leading horse stopping on the racetrack to ask the punters for a few bob? It’s a real mystery, all right.

Sinn Fein is in a bit of a pickle, as it stands, heading into Thursday’s vote. By all accounts, it seems almost dead certain to lose Foyle to the SDLP, and very few people have them as favourites to take Nigel Dodds’ seat in North Belfast. Add to that the fact that Fermanagh-South Tyrone is perpetually on a knife edge between Sinn Fein and the Unionist candidate – there were about 700 votes in it the last time – and there is a very realistic prospect that the party could be reduced to just five seats out of eighteen in Northern Ireland.

That’s not just bad news for Sinn Fein, of course. Every seat they win in Northern Ireland is one less that Boris Johnson has to win in over in Great Britain to get a majority, because Sinn Fein don’t take their seats. With a full house, Boris needs 326 seats to get his beloved Brexit done. With seven Sinn Feiners, he needs just 322. Sinn Fein are worth four seats to the Tories at the moment, and every Sinn Fein loss makes his job just that little bit harder.

Maybe this letter wasn’t circulated by Sinn Fein in an attempt to stop Eastwood. Perhaps it was written in number 10, as part of the plan to Get Brexit Done.