Wednesday 29 May 2019

The devil and André Sainte-Laguë

In a posting at the end of last month, I warned how an ignorant (or malevolent) decision made by Labour Home Secretary Jack Straw twenty years ago could give disproportionately too many European Parliament seats to the Brexit party. By implication, the Liberal Democrats would not gain the number of MEPs they were entitled to according to the percentage of votes cast. So it has turned out. Less expectedly, Conservatives also missed out and Labour would have had to do remarkably better in South-West England to have even got a sniff.

I am by no means an electoral systems wonk, so what follows is the result of hurried mugging-up. The d'Hondt method of allocating seats from party lists is in use in the UK and several other countries round the world. It is known to favour larger parties. The main alternative, devised by André Sainte-Laguë, was actually first thought up by the almost legendary US statesman Daniel Webster. The basic procedure is set out by the helpful German company Polyas which specialises in on-line voting systems.

Armed only with O-level maths and a Which? pocket calculator, I tried it out first on a simple four-seat selection and one close to home: the Welsh EP election. (All figures on which my calculations are based are from wikipedia which tends to be more accurate than the BBC when it comes to election reporting.) Not expecting much change, I was surprised to find that Webster/Sainte-Laguë actually awarded the fourth seat to Lib Dems rather than Brexit. (The other three seats were unchanged: Brexit, Plaid Cymru and Labour.)

So, on to Scotland, where the actual outcome was 3 SNP MEPs, 1 Brexit, 1 Liberal Democrat and 1 Conservative. Applying Webster/Sainte-Laguë on the proverbial back-of-the-envelope gives 2 SNP, 1 Brexit, 1 Lib Dem, 1 Con. and 1 Labour.

The moral is that short-term expedients which give you undue advantage when you are on top can exaggerate your fall when you slide down the greasy pole. Labour must be praying that neither Brexit nor Plaid Cymru win a majority of constituency seats when 2021 and the next Welsh general election come round.

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