Back in the summer, Lewis Baston wrote a fascinating geeky piece about which Westminster constituencies in the UK have voted for the winning party in the most elections. Both Dartford and South Derbyshire / Belper voted Labour in 1964 and 1966, Tory in 1970, Labour in both 1974 elections, Tory in 1979, 1983, 1987 and 1992, Labour in 1997, 2001 and 2005, Tory in 2010, 2015, 2017 and 2019 and Labour in 2024. However, both of them voted Labour in 1959 when the Conservatives won, so the chain stops in 1964. If you allow a couple of lapses from an otherwise perfect record, Buckingham (now Buckingham and Bletchley) has voted for the winning party every time since 1868, except in 1929 and the two 1974 elections.

He then goes on to consider Scotland and Wales separately, and to define the bellwethers in each case as those where the winner in a particular seat matched the party which won the most seats in Scotland or Wales. Labour has always won in Wales since 1922, and there are six constituencies which have consistently voted Labour since then (three of which voted for the Coalition in 1918). In Scotland, if you allow both Labour and Conservative seats in 1951 when the two parties tied, Central Ayrshire has voted for the Scottish winner since it was created in 1950.

Baston leaves out Northern Ireland, because there is no seat that elected both a Sinn Fein MP in 2024 and a DUP MP in 2019. But if we apply a bit more generosity (a la Buckingham and Bletchley), we can get a bit more texture.

For Northern Ireland, we have to start in 1922, both because that’s when it became a separate entity and because the six counties had had a lot more MPs before then, so it’s more difficult to assess what the successor constituencies are. From 1922 there were six single-seat territorial constituencies (plus the Queen’s University of Belfast), and also three two-seat constituencies, which after 1950 were split into six single seats (and the QUB seat was abolished). Five new seats were added to the map in 1987 for a total of seventeen, and an eighteenth was added in 1997.

The Ulster Unionist Party won the most seats in Northern Ireland at every Westminster election from Partition to 2001 (we can be generous and count in all the other MPs elected on the UUUC ticket in the two 1974 elections, but it doesn’t make much difference in the end). The DUP then won the most seats in 2005, 2010, 2015, 2017 and 2019, and Sinn Fein won the most in 2024, so we are looking for seats that voted most often for the winners in recent elections.

Up until 2019, three of the seats created in 1983 had an unblemished record of going with the biggest party in Northern Ireland: East Antrim, Lagan Valley and Upper Bann, which all switched from UUP to DUP in 2005. If you allow Lagan Valley and East Antrim as partial successors to the old South Antrim seat (and to the previous County Antrim two-seater), and Upper Bann as a partial successor to the old Armagh seat, the record goes for almost a century from 1922 to 2019.

East Londonderry (considered as a successor to the old County Londonderry) and South Antrim itself (considered as a successor to the old South Antrim and the previous County Antrim) missed only one election in those 97 years (East Londonderry won by Gregory Campbell of the DUP in 2001, South Antrim by Danny Kinahan of the UUP in 2015). Strangford also missed only 2001 since its creation in 1983, but its predecessor seats were a bit more variable.

However, that’s no good for the present day, because none of those seats were won by Sinn Fein in 2024. Most of the current Sinn Fein seats have been held by Sinn Fein or the SDLP for decades, so none of them are potential bellwethers either. Of today’s SF seats, the one that is closest to a bellwether constituency is North Belfast, which has gone with the largest party at each Westminster election since 1922 with three exceptions: 1979 when Johnny McQuade won it for the DUP, 2001 when Nigel Dodds took it also for the DUP, ahead of the 2005 surge, and 2019 when John Finucane of Sinn Fein defeated Nigel Dodds. It looks pretty safely in the Sinn Fein group for the time being.

There is also an anti-bellwether seat, which has never voted for the Northern Ireland-wide largest party since its creation. That seat is Foyle, which has been held by the SDLP from 1983 to the present day, with the exception of the 2017 election when it was taken by Sinn Fein. North Down has only once voted for the province-wide winner since 1983, and that was in 2001 when Lady Sylvia Hermon first won it for the UUP. She was still UUP in 2005, but all the other UUP seats were lost.

(I wonder if there are also similar anti-bellwether seats for the UK as a whole, or for England, Scotland and Wales?)

I had a quick look to see if one could make the same calculation for Assembly constituencies, to identify which has a representation which is proportionally the most similar to the Assembly as a whole. It’s very difficult to assess that. Right now, the answer would probably be North Belfast again. In 2022 it elected two members from the two biggest parties (the DUP and Sinn Fein) and one from the third biggest (Alliance), and similarly in 2019 (when the third largest party overall, and the fifth North Belfast MLA, were SDLP). In 2017, when there were six seats per constituency, North Belfast again came closest to the make-up of the Assembly but did not quite match it, with three DUP MLAs, two SF and one SDLP (whereas the UUP had the third largest number of seats at that election). This probably demonstrates that the concept of a bellwether seat cannot really be adapted to a proportional multi-party election.

And I’m not going to attempt to apply the concept to the Dáil. That’s for stronger-minded psephologists than me.