Today is the UK referendum on electoral reform. Brits get to choose between FPTP and AV, and the vast majority of my political posts on this blog have been about it, including the much-read AV versus FPTP—just the facts, man. And an interview with someone a bit right-wing who doesn’t exist. (Note to non-Brits and the politically agnostic—don’t worry, I’ll be back to mostly banging on about tech and gaming next week.)

A bunch of people have asked me to explain in a little more depth about how the voting systems work, and so here’s a brief overview.

Briefly, FPTP (our existing system) works as follows:

  • Vote for one candidate
  • The candidate with the most votes wins the seat

The main strength of FPTP is that it’s dead simple; it’s also largely fair in head-to-head(ish) seats that are mostly a contest between two candidates.

The main problems with FPTP are that its winner-takes-all approach leads to tactical voting in more complex seats, and it also enables someone to take a seat with a minority vote share. There’s also the spoiler effect, which the Tories have used well in recent years—the ‘left’/moderate vote splits, enabling the Tories to win seats that Labour or Lib Dem supporters would have been happy(ish) going to the other candidate.

AV works as follows:

  1. Vote for as many candidates as you wish, ranking them in order
  2. If a candidate has 50% of the vote, they win the seat, otherwise:
  3. Second-choice preferences for the lowest-placed candidates are redistributed.

2 and 3 loop until a candidate has over 50% of the vote. The end result is a winner with the direct backing of core supporters and indirect backing of people who think they are at least ‘better than the other guy’. This kills the spoiler effect.

How could this work in practice? Well, in a seat where a candidate already has a really strong showing, winning over 50% of votes, AV makes no difference at all. This makes sense, since the candidate clearly has majority backing from their constituents. But let’s travel back to a made-up 2010 and a fairly tight contest in a UK seat, with three candidates: Left Lib, Lefty Lab and Righty Con. Righty Con’s a lazy fucker, but he wins elections because the Lefty votes are split and because he has enough core support to squeak through each time. But in the expenses scandal, it was shown that he’s expensed a £25,000 hat and a decade’s worth of Smarties, and so polling suggests things will be tight.

Under FPTP, this is what happened in Made-Up On Thames in 2010:

Lefty Lib: 29%
Lefty Lab: 35%
Righty Con: 36%

As you can see, Righty Con only had a slim majority over Lefty Lab, but the majority of the voters didn’t want him. In fact, all the Lefty lot are now hugely pissed off and confused, and they’re banging on about tactical voting next time and how they should have voted for someone who wasn’t their first choice last time. But that might not have made any odds because not everyone would have done this and OH IT’S TOO CONFUSING.

In a magical world where AV actually wins the referendum today, here’s what happens in 2015, with the exact same turnout:

Lefty Lib: 29%
Lefty Lab: 35%
Righty Con: 36%

Man, those guys don’t learn, do they? The exact same result. Hurrah for Righty Con!

BUT WAIT! We have AV now, and so the votes don’t work in the same way. Lefty Lib is last, and so he is eliminated (possibly by firing squad) and his second-choice votes are redistributed. The vast majority of Lefty Lib supporters thought Lefty Lab was a better bet than Righty Con, and so this is what subsequently happened:

Lefty Lab: 58%
Righty Con: 42%

Lefty Lab now wins, backed directly by 35% and indirectly by the majority of the remainder. In 2020, Righty Con will have to work harder to appeal to a broader range of people, rather than being a lazy git.

And that, ultimately, is your choice today. I’m voting yes to AV. The system is imperfect and not what I’d choose if we had a larger selection of tasty reform-oriented treats, but I think AV betters FPTP in important areas. However, even if you disagree, go and vote. The UK rarely gets chances like this, so make the most of it and make your voice heard.