Hi, I'm John MacKay. And THIS...is the STV news.

In the wake of the local by-elections in Glasgow and Hamilton, in which the SNP required big swings simply to "hold" four seats, regular commenter bjsalba sent me this suggestion -

"You wrote "Welcome to the mad, mad world of by-elections conducted under STV."

Might be a good time to review STV in terms of how it works at the main elections - and how it works (or doesn't) in by-elections. Do you have any suggestions for an alternative system? Or changes to improve the current system? How is it done (or not done) in other European Countries?"

STV may have long been the Holy Grail for some electoral reformers, but it actually isn't a particularly popular system in Europe - to the best of my knowledge, it's only used here (for local elections), in Northern Ireland (for Assembly, local, and European elections), and in the Republic of Ireland and Malta (for all elections). So there are limits to what we can learn from international comparisons. The Republic of Ireland take the same approach to filling vacancies that we do - they hold by-elections, and just live with the fact that it undermines the proportionality of the system. By contrast, in the Northern Ireland Assembly, new members are simply co-opted from the same party that previously held the seat. That 'feels' much less democratic, but it actually ensures that the composition of the chamber remains more in line with the voters' wishes (albeit their wishes as expressed in an election that may have been a long time ago).

Neither approach is perfect, but then neither one is an automatic feature of STV, so criticism of any discrepancies that arise is not really a criticism of the voting system itself. I used to be an enthusiast for STV, but what started to change my thinking was the last Irish general election, when it became obvious in the run-up to polling that Fine Gael would probably win an outright majority if they received just 40% of the first preference vote. (In the end they fell short with 36%.) That just doesn't seem proportional enough to me. The problem is that STV discriminates against smaller parties, by creating quite a high de facto threshold to achieve any representation at all. It's not quite as bad as first-past-the-post in that respect, but it's bad enough.

The reason why STV is so highly regarded by anoraks is that it maximises voter choice. But there are other systems that allow voters to choose between candidates from the same party (as well as between different parties), while still producing more proportional outcomes.

* * *

I've been keeping an eye on the Labour leadership betting prices at Betfair, and I can't make head nor tail of what's going on. Jeremy Corbyn finally became the favourite for two or three days, before being overtaken again by Andy Burnham at the start of the week. Burnham then strengthened over recent days to become quite a clear favourite, but is suddenly trailing Corbyn again (marginally) right at this moment. Doubtless, the likes of Neil Edward Lovatt will be telling themselves that these fluctuations must reflect inside knowledge or a mysterious "wisdom of crowds" effect, but I have my doubts. I think it's more likely to be a herd instinct - punters assuming that other punters have inside knowledge, thus creating a snowball effect out of nothing.

Rationally, it seems to me that Corbyn should be an odds-against favourite. In other words, there is a greater than 50% chance that he will be beaten by either Burnham or Yvette Cooper in the final run-off. But as Corbyn seems to be virtually assured of a place in that run-off and the other two are not, his price should definitely be shorter than any other individual candidate's.