You know, Bristol has been mucking up the nice neat map of England's counties for nearly six and a half centuries now.

As with so many major British cities, it's sited on a river, the Avon. That forms the boundary between Gloucestershire and Somerset, so from very early in its history the city had one foot in both counties. That soon made things complicated, from a medieval governance point of view, so in 1373 a charter created the “County of the Town of Bristol”. Effectively Bristol invented the metropolitan county, 600 years early.

“Greater Bristol”. Image: Steinsky/Wikipedia.

More than half a millennium later, the administrative map of the area is still a mess. From 1974 there was a county called Avon, which despite being a sort of Greater Bristol was a non-metropolitan county; but that got abolished in 1996. Once city regions came on the scene, it seemed as if Avon might be coming back – but then one of the four authorities that would have been required, North Somerset, decided it didn't want to play.

So the result is that what is still effectively the Greater Bristol mayoralty will have powers over the City of Bristol, its north-eastern suburbs in South Gloucestershire, and its south-eastern ones in Bath & North East Somerset. The south-western ones, though, are untouched.

The West of England. 1. Bristol, 2. South Gloucestershire, 3. Bath & North East Somerset. Labelled 4 is North Somerset Council, which rejected plans for the Authority. Image: Wikipedia.

Oh, and it's not Greater Bristol, nor even Avon, any more. It's now the West of England – despite the fact that's a label that could plausible stretch from Swindon to Penzance.

Anyway, that's enough nerdery, let's talk about the mayoral election.

The race

The funny thing about this one is that, uniquely among this year's mayoral elections, it might genuinely a three way contest.

These elections, remember, aren't using the familiar First Past The Post electoral system, but the more complicated Supplementary Vote one. Each voter gets both a first and second preference. Once the authorities have counted up all the first preferences, assuming nobody has more than 50 per cent – and they won't – then all but the top two candidates will be eliminated, and their votes re-distributed by second preference.

The result of this is that a broadly tolerable candidate who comes second in the first round could win, ahead of a broadly loathed one who comes first.

The yellows

Which leads us neatly to the Liberal Democrat candidate Stephen Williams. The MP for Bristol West from 2005, and a junior minister in the coalition government, Williams lost his seat in the 2015 Liberal Democrat wipe out.

But his parliamentary experience means he's a relatively prominent local figure – more so, probably, than his rivals. What’s more, he could plausibly win: make it to the top two, and second preferences could carry him over the top. If any Liberal Democrat stands a chance of becoming a mayor next week, it's Williams.

Well, you'd hope so.

As to policy, his manifesto is split into two big themes, the economy and transport. Between them they contain a dizzying number of proposals, of varying degrees of plausibility. To name a few: broadband for the region's rural villages, scrapping the Severn Bridge toll, creating spaces for start ups, cashless payment for buses, rail electrification, new railway stations, a Bristol Circle line, a tram to the airport, a whole bevy of road schemes, and campaigning against Brexit. Phew.

The blues

The Tory candidate is Tim Bowles, a councillor in the leafy suburbs of South Gloucestershire. To give you a sense of his political identity, here's a picture of Tim standing in a field:

Tim hasn't published a manifesto, but his inconsistently punctuated website does contain a number of news releases and "campaigns" which offer a sense of his priorities. He talks a lot about the need to build on brownfield and protect the area's green spaces from housing development. He also talks a lot about building new roads. You might think this a contradiction. We couldn't possibly comment.

One of Tim's campaign pages promises, "I'll stop OUR interests being ignored by the Bristol Labour party", which gives a sense of the region's political faultlines. The city itself is fairly red, and last year elected Labour’s Marvin Rees as its mayor. But that only accounts for slightly under half the region's population (450,000, compared to 460,000 in the other two boroughs). And, to quote Bowles' website:

Labour control the Bristol Mayor, and have nearly half their local Councillors representing Bristol. If we allow Labour to win we risk the interests of our area being ignored and over-ridden. Avon County Council did that and that is why it was abolished – it mustn’t come back!

In other words, Bowles is very much the candidate of the suburbs, that are very definitely NOT part of Bristol thank you very much. If he wins, it’ll be fun to watch him bash heads with the pre-existing elected Labour mayor of Bristol, Marvin Rees.

The reds

Labour is likely to do best in Bristol itself. Its candidate its Lesley Mansell, an NHS diversity manager and councillor in the village of Westfield, in north east Somerset.

She's promising more home, better jobs, better internet connections, and to "defend tenants against unscrupulous landlords", by introducing an ethical lettings charter. She's also promising a whole bunch of transport policies: creating an integrated transport authority for the region, introducing a smart card system, increasing the frequency of a rail services, better cycling lanes, you know the drill.

She's put rather more effort into her policies than Bowles, publishing an 11 page manifesto which you can read here if that's your bag.

The rest

There are three other candidates in the race, but none of them are going to be mayor so let's get through them pretty quickly.

The Greens are offering Darren Hall, a former RAF engineer, who's talking about green energy, better insulated homes, more regulated public transport and opposing hard Brexit. He's also cleverly bagged the web address "metromayor.org.uk" for his campaign, so great SEO there, Darren.

UKIP's candidate is Aaron Foot, who is pushing a similar platform to Bowels: protect green spaces; end the war on motorists (yes). He's also promising to create an online platform for direct democracy ("For the first time, a politician will be the servant of the people, not the other way around").

Last but not least, there's the independent John Savage, the executive chair of the Bristol Chamber of Commerce. He's gone beyond publishing a manifesto and published an entire book about his vision for the region ("2050 - High In Hope"). He seems to have put a lot of effort into all this, bless him, but it’s not as crazy as it sounds: in 2012, Bristol elected the independent George Ferguson as its mayor on a Bristol First ticket.

Who will win?

For reasons outlined above this is by far the hardest of the metro mayor elections to call. Our old friend John Curtice reckons that the 2015 results in the region were as follows:

Con: 36.8%

Lab: 28.1%

LibDem: 14.1%

UKIP: 11.1%

Green: 9.5%

But that was two years ago, since when Labour and UKIP have probably collapsed, and the Tories and LibDems have probably climbed. All that, one might think, would point to a victory for Tim Bowles.

And yet – there's that supplementary vote thing to consider. Bowles is extremely unlikely to top 50 percent on the first round. And those second preferences might change everything.

For what little it's worth – and it is little – Ladbrokes currently has Stephen Williams and Tim Bowles at 11/10, meaning that they both have almost a 50 per cent chance of victory. Leslie Mansell is on a rather impressive 8/1, which isn’t much better odds than John Savage on 12/1. The Greens and UKIP are on 66/1 and 100/1 respectively.

We shall know soon enough.

Jonn Elledge is the editor of CityMetric. He is on Twitter as @jonnelledge and also has a Facebook page now for some reason.

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