Boundary changes are both a curse and a blessing for the psephologist. The process of sitting down with copies of the maps of changed districts, and allocate votes for the various parties in past elections to small fragments of constituencies, and then adding them up and trying to believe the answer, is one of mind-numbing complexity. On the other hand, one tends to find that very few other people have tried it, and that fortunately those who do tend to reach much the same conclusions.
The boundaries for this year’s Assembly elections are being used for the second time, following last year’s Westminster election, and probably for the last time, assuming that the House of Commons is reduced to 600 MPs as scheduled and that there is no premature dissolution. They replaced the 18-seat boundaries which had been used for every election from 1996 to 2007. In some cases – the five south-western constituencies, and North Down – there was in fact no change. Some of the other seats, however, were quite drastically altered.
The biggest net change is to Strangford, where seven Castlereagh wards were moved to the Belfast constituencies in return for three South Down wards being added at the other end. I make the net shift of 2007 voters about 3,000 unionist votes (2,400 DUP and 600 UUP) out, about 200 nationalist votes (mostly SF, though they are still a long way behind) coming in, and Alliance down by a net 800 or 900. Given that the seat had the closest result in the entire 2007 election, the DUP’s Michelle McIlveen defeating the SDLP’s Joe Boyle by a mere 31.05 votes, one has to count it as rather likely that the SDLP will make the breakthrough here which they have been close to in the last few elections.
The second biggest change is East Belfast, where five of those Castlereagh wards are added from Strangford at the cost of two going to South Belfast. Here I make the net change of voters 3,600 extra unionists, based on their 2007 performance (2,600 DUP, 800 UUP and 200 others); 300 fewer nationalists (200 SF, 100 SDLP); and 200 more Alliance. These shifts are, however, eclipsed by the massive change in voter behaviour which saw Naomi Long elected Alliance’s first Member of Parliament in 2010, defeating DUP leader Peter Robinson; the 2007 results are of limited use as a guide to voting in 2011.
North Belfast is one seat where, though the changes on the ground are drastic, with six Newtownabbey wards being added, the electoral consequences are fairly minimal. I reckon that SF and the DUP in North Belfast both gain 1500 voters who supported them elsewhere in 2007; but the SDLP gain 1000, the UUP 900 and Alliance 700. It barely changes the percentage vote share for the parties.
South Antrim is a slightly different matter. It loses five wards to North Belfast and gains one from Lagan Valley; I make the net shifts 800 fewer unionist voters from 2007 (fairly equally split between DUP and UUP), 500 fewer Alliance voters and 1,500 fewer nationalist voters (perhaps 850 SF to 650 SDLP). In 2007, the SDLP’s Thomas Burns beat the DUP’s Mel Lucas for the last seat by less than 1,200 votes, so all one can say is that his defence of his seat has been made tougher.
South Belfast gains two wards from East Belfast and two from Castlereagh. By my count they have 2,200 unionist voters (1,600 DUP and 600 UUP) in 2007, 1,100 nationalist voters (700 SF and 400 SDLP) and also 700 Alliance voters. In 2007, Sinn Féin’s Alex Maskey was only 700 votes ahead of the second DUP candidate, Christopher Stalford, so again his defence has been made tougher.
Lagan Valley, as noted above, loses a ward to South Antrim and, more significantly, one-and-a-half wards to West Belfast. I reckon that removes 1,200 unionist voters (900 DUP and 300 UUP), little difference to Alliance (for whom the areas in question are not hotbeds of support) and 3,800 nationalist voters (2,400 SF, and 1,400 SDLP) – this is almost half of the 7,900 Nationalist voters of 2007, and exactly half of the SDLP’s support. It’s very difficult to see a nationalist seat being retained in Lagan Valley in that context.
East Antrim, however, goes the other way, losing one ward to North Belfast and gaining three from North Antrim, with a net loss of 900 unionist votes (600 DUP and 300 UUP) and 200 Alliance votes, and a net gain of 1,600 nationalist votes (900 SF, 700 SDLP). The SDLP missed their seat here by less than 900 votes in 2007; if they can remain the larger nationalist party (which they were not in 2010) they should be able to make a gain.
West Belfast gains those one-and-a-half wards from Lagan Valley and thus also gains 400 unionist votes (300 DUP and 100 UUP) and 2,800 nationalist votes (1,800 SF and 1,000 SDLP). I don’t see that changing the results very much.
South Down loses three wards to Strangford. I reckon that the 2007 levels of support in the area in question was 2,700 unionists (1,700 DUP and 1,000 UUP) and 1,000 nationalists (evenly divided). This may be enough to gain nationalists a seat, but it may not – the UUP’s John McCallister beat the SDLP’s Michael Carr for the last seat by over 3,000 votes in 2007, which looks on the face of it like a sufficient cushion.
East Londonderry and Foyle have a straight transfer of two wards to the former from the latter. I make the 2007 results in the area concerned about 700 unionists (600 DUP and 100 UUP), and 2000 nationalists, equally split between the two main parties. (Again, not a strong area for Alliance.) This doesn’t make much difference in Foyle; it nudges nationalists closer to a third seat in East Londonderry, but probably not close enough.
Finally, North Antrim is very much affected by the loss of three Moyle wards to East Antrim: a heavily nationalist area, I make the shift 900 SF voters, 700 SDLP voters and a handful of unionists. The SDLP’s Declan O’Loan had a comfortable margin of more than 2,000 votes over the DUP’s Deirdre Nelson, but that becomes much less comfortable under the new boundaries.
In summary, one can see the boundary changes having the following likely effects:
Unionist gain from nationalists: almost certain in Lagan Valley, possible in South Antrim, South Belfast, and North Antrim.
Nationalist gain from unionists: almost certain in Strangford and East Antrim (though Alliance seats in both are also potentially at risk), possible in South Down.
But of course, this analysis is based on voters supporting the same parties in 2011 as they did in 2007, whatever the boundaries may be; and we can be pretty certain that that will not happen.