In election season, any and every statistic that adds to the case for your candidate is a contender for being slapped on a leaflet and put through the letterbox. (And, if you’re the Lib Dems, literally any statistic can be put into a dodgy bar chart, regardless of what it actually says).

Following the West of England metro mayor results, there is much excitement among Labour and Lib Dem camps about how Bristol West voted. Labour gained the biggest voteshare, with Lib Dems second, and Greens third.

The Lib Dems in particular are going down the ‘two horse race’ route, despite having only just used exactly the same argument in the West of England contest with the end result of letting the Tories in. Labour want their decent first place to be taken as an early declaration of victory.

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Personally, I think the Labour vs Greens narrative has been firmly established in Bristol West, and the Lib Dems are stretching credibility, even by their own standards, by relying on such an arcane contortion.

However, there will be social media arguments ahead, and it’s always good to have a rebuttal post on standby.

So here’s why the Bristol West voteshare of the West of England metro mayor election is not a good gauge of party support in the General Election:

1. Bristol Green Party & National prioritised Bristol West, not the West of England

One factor that has had a big impact on election results is campaigning. As a general rule, there is a level of background support for parties that shows itself when no one mounts a serious campaign.

Without door-to-door campaigning, people aren’t exposed to direct contact with a party’s arguments, and so rely on pre-existing ideas about what each party stands for. Green support didn’t magically appear in Bristol West: it’s the result of years of hard work by local activists (and some good fortune).

Bristol Green Party has been pretty single-minded in its targeting strategy: Bristol West is everything. Whilst it’s true that the national party is putting resources into the Bristol West campaign, every local branch knows that campaign funding from the central party is campaign-specific, and has strings attached. You don’t just spray money locally: you demand a campaign plan, a budget and evidence that what you’ve paid for has been delivered.

As a result, campaigning efforts have been focused on Molly Scott Cato’s Bristol West campaign (which could get the Greens their second MP), not Darren Hall’s West of England metro mayor (which the Greens were never going to win, and which was being contested by a candidate with dubious credentials among green campaigners and voters in Bristol).

By contrast, the Lib Dems threw the kitchen sink at their West of England campaign, and Labour linked up their metro mayor campaign with the beginning stages of their General Election campaign.

As a rule, Labour are better at mobilising their activists, and have better campaign discipline than other parties. So in Bristol West, it’s worth viewing the three campaigns in this way: Labour (good mobilisation, metro mayor & General Election campaigns integrated), Lib Dems (high intensity campaigning, convincing “only we can beat the Tories” narrative, candidate lost the constituency two years previously), Greens (minimal campaigning, ambiguous support for candidate among core vote).

To be honest, given these factors, I’m impressed that the Green vote ended up only a couple of thousand votes behind the Lib Dems. A different Green candidate (e.g. Ashley Cllr Jude English, who I voted for in our internal ballot to decide the candidate) would have finished second in Bristol West. And if the Lib Dems had fielded a different candidate (Stephen Williams didn’t just lose Bristol West, he dropped 29 percentage points: that’s political career ending), they’d have come first, and probably won the metro mayor too.

2. People vote according to the election they are voting in

This is one of my core rules for thinking about elections. When I use the bar chart of the 2015 Bristol West results, I’m not predicting the 2017 result: I’m saying to potential Green voters, “Here is evidence of Green support in the constituency, so it is reasonable to think that your vote won’t be wasted”.

Every election must be fought from scratch. There were Green councillors elected in 2015 who lost their seats to Labour just one year later at the all-out elections. Every election result is a snapshot of what happened on polling day.

If the main plank of your campaign is “The voteshare for first preferences in the Bristol West sub-section of the West of England metro mayor demonstrates that the Greens can’t win the constituency in the General Election”, then, with apologies, you are a shyster (and probably a Lib Dem; Labour’s best angle is to point out they have the incumbent).

Another of my core rules is that voters are not stupid. Put these rules together, and the end result of the kind of campaign the Lib Dems are running in Bristol West is another big drop in voteshare.

3. Low turnout dramatically skews results

The turnout for the West of England metro mayor was 29 per cent overall, with turnout in Bristol West at 31 per cent. When turnout drops to 33 per cent or less, you get a pundit’s election. That is, the one thing you can be sure about is that the majority of the people who turned out are people who have long-standing political opinions and/or regularly comment on political issues. In other words, only the most politically engaged people have turned out.

This means that factors like tactical voting and more in-depth knowledge of what’s happening in local politics have scaled up effects. Ironically, this makes it harder to know what the same constituency is going to do in a General Election, because you are seeing the voting behaviour of people with a higher level of political engagement. This behaviour is not indicative of how most people will vote.

In Bristol West, the General Election turnout can be expected to be around 70 per cent. That’s more than double the people who turned out to vote for a metro mayor in the constituency. This alone is enough to render the local voteshare from the metro mayor contest meaningless.

4. Lib Dems misled voters

The Lib Dems are in trouble. The central premise of their metro mayor campaign was that only they could beat the Tories. Many people found themselves struggling with the dilemma of not wanting to vote Lib Dem (sorry yellow team: the coalition was only two years ago, people do remember) but also not wanting to let the Tories in.

This premise was ;evidenced’ by that mainstay of British elections, the dodgy Lib Dem bar chart. In this instance, the bar chart was of betting odds showing Tories and Lib Dems ‘neck and neck’ (a two horse race!) with everyone else languishing on distant no-contender odds.

The awful thing about this strategy is that it confused people over how to vote in a supplementary vote system, because it was using first-past-the-post logic. Two horse race arguments only apply to first-past-the-post. In supplementary votes, if the top choice has less than 50 per cent of the overall vote, then the first and second choices go into a second race between the two of them.

And then the Tory won. And Labour came second. And the Lib Dems came third. And suddenly, as if waking from a terrible dream, people started exclaiming things like, “I can’t believe I let the Lib Dems fool me again!”.

Stephen Williams shouldn’t underestimate just how much personal culpability he has in the eyes of Bristol West voters for the Tories winning the metro mayor. Maybe if the General Election was in two years’ time, that would recede from memory. But he was announced as Bristol West candidate barely a week after handing the West of England to the Tories, so he should expect a lot of people to punish him at the ballot box as a result.

Simon Stafford-Townsend is a psychotherapist (The Bristol Therapist) and political blogger (PsychoPolitico). He lives and works in Bristol West with his partner and child, and stood as a candidate for the Green Party in Ashley ward in the 2016 local elections.

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