Whatever Happened To Multi-Party Marginals?

I had a concern about last week's general election - namely that as the party system fragmented further, there would be an element of randomness in the result, with many seats being won on small (say less than 30%) shares of the votes, and a rise in 3-way and 4-way marginals. I would not have been surprised if a genuine 5-way marginal appeared (my money - if I were a betting person - would have been on Brecon & Radnorshire).

Instead, the opposite has occurred, with these multi-party marginals becoming rare. As the party system fragments it has also solidified into a collection of 2-party systems, with the overwhelming majority of seats falling into one of these categories:

• A safe seat for one party, with the identity of the runner-up being only of interest to political anoraks like myself
• A marginal seat for one party, with another party being the sole clear challenger

There are now only 4 seats with less than 10% of the vote between the first and third parties:

Constituency	Gap between 1st and 3rd	Winner	Runner-up	3rd
Thurrock	1.97%	Conservative	Labour	UK Independence Party
Belfast South	7.32%	Social Democratic & Labour Party	Democratic Unionist Party	Alliance Party of Northern Ireland
Upper Bann	8.13%	Democratic Unionist Party	Ulster Unionist Party	Sinn Féin
Ynys Môn	9.96%	Labour	Plaid Cymru	Conservative

The closest gap between first and fourth place is 10.68% in Belfast South, with Sinn Féin in fourth place. In Great Britain the closest is 14.11% between the Liberal Democrats and UKIP in Southport.

With 15.44% between the SDLP and the Ulster Unionist Party, Belfast South has the smallest gap between the first and fifth candidates.