What do the new boundaries mean for Cambridge’s local elections?

As Cambridge goes to the polls on Thursday in the local and mayoral elections, we’ll get some indication of how political opinion is moving in the city ahead of June’s General Election. The last General Election, in 2015, was held on the same day as the local elections, and there was a marked difference in voting patterns. Here’s a comparison of how the Cambridge constituency voted for its MP (darker colours) and local councillors (lighter colours):

As you can see, while Daniel Zeichner won his seat from Julian Huppert with a knife-edge 1% margin, Labour council candidates outpolled their Lib Dem rivals more comfortably, with an 8% lead. The other notable feature was that Green MP candidate Rupert Read scored less than half the vote share of his council colleagues.

This year the Cambridge local election results will be announced after 9am on Friday 5th of May, rather than overnight. As the results come in, we’ll have some idea of how the parties have fared relative to 2015. If Labour manage a bigger margin of victory in the local elections, then it’ll be good news for Daniel Zeichner, but if the Lib Dems close the gap, then Julian Huppert will be more hopeful of recapturing the Cambridge seat. But because of the difference in performance between the local and general elections, it’s quite possible that Labour could lose the Parliamentary contest while winning locally at Council level.

As well as the impending General Election, another factor making this year’s local elections harder to predict than usual is the boundary changes. As I’ve discussed in a previous article, most of Cambridge’s County Council seats have new boundaries this year, making it harder than usual to predict the likely winners. To try to throw some light on the situation, I’ve put together projections for each new seat, estimating the votes cast in each of the new boundaries for the last five local elections.

It’s impossible to know exactly how many votes were cast within the new boundaries at previous elections, but we can make an educated guess. We know how much of each old seat is included in each new seat, so by taking appropriate proportions of previous election results, we can estimate the votes cast at previous elections within the new boundaries. For example, the new Queen Edith’s seat consists of 87% of the old Queen Edith’s seat, 26% of the old Coleridge seat, and 7% of the old Cherry Hinton seat. So if you add up the previous election results in those seats in those proportions, you get an estimate of how people living within Queen Edith’s new boundaries voted at previous elections. This method isn’t perfect, of course – party support isn’t uniformly distributed across seats, and people don’t just vote for the party label – but it does give us some idea of the baseline that the parties are starting from in each of the new seats. If you’re interested in the exact ingredients of each seat, refer to Colin Rosenstiel’s tables here – electoral divisions (EDs) are the new seat boundaries for this year’s County Council elections; wards are the old boundaries, which will still be used for City Council elections.

Let’s look at the projections for each of the new seats. As ever, remember that I’m a Lib Dem member, so adjust your confirmation bias accordingly.

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Unlike all the other County Council seats in Cambridge, Abbey’s boundaries are unchanged, so this graph simply shows the previous local election results. As you can see, Labour have enjoyed a commanding lead over other parties in recent years.

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The new Arbury seat consists of 86% of the old Arbury seat, 11% of old West Chesterton, 10% of old Castle, and just 4% of old King’s Hedges – so this graph shows the previous results for all those seats added up in those proportions. This heady mix still gives Labour a pretty comfortable lead over the Lib Dems, though less so in 2015, the last General Election year.

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With Castle, the projection method does break down a bit, though it still gives an interesting illustration of the electoral situation this year. The new Castle seat is made up of just 57% of the old Castle, plus 20% of old West Chesterton, and 14% of old Arbury. The Castle Independents, huband-and-wife team John Hipkin and Marie-Louise Holland, have won Castle on the old boundaries in four of the last five years – the exception being 2015, when they did not stand. However, with a big chunk of the old Castle gone from the new seat, and parts of two other seats mixed in, the projection shows a knife-edge Lib Dem/Labour contest in recent years, with Labour ahead last year, and the Independent vote some way behind. However, this is somewhat misleading, because there were no Independent candidates in either Arbury or West Chesterton in recent years, and if there had been they would certainly not have got zero votes. This factor artificially lowers the projected Independent share of the vote – indeed, I think John Hipkin is still front-runner even on the new boundaries. But it does illustrate the challenge that the Castle Independents face in persuading the “new” Castle voters to support them – and we certainly can’t rule out a surprise result in Castle this year.

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The new Cherry Hinton seat is made up of 93% of the old Cherry Hinton, plus 39% of the now-dismembered Coleridge seat. This doesn’t do very much to change its electoral makeup, which in recent years has been dominated by Labour.

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The new Chesterton seat promises one of the most intriguing contests this year, with well-known Lib Dem councillor Ian Manning facing a strong challenge from Labour newcomer Kelley Green, who has proved herself to be a formidable campaigner. The new seat is made up of 68% of the old East Chesterton, plus 60% of the old West Chesterton. The projected results show a close contest between the two main Cambridge parties. Labour will take heart from the 2016 projection, which put them 8% ahead on the new boundaries, while Lib Dems will note that in 2013, the last time Ian Manning stood for the County Council, they had a 5% advantage.

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The new King’s Hedges contains almost all – 96% – of the old King’s Hedges, plus 32% of the old East Chesterton and 9% of the old West Chesterton. This mixture slightly reduces the lead Labour had on the old boundaries, but not by a great deal – Labour will be hoping for a comfortable win ahead of the Liberal Democrats.

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Market is enlarged by the boundary changes, and includes all its previous voters plus 23% of the old Castle ward. This doesn’t change its basic makeup very much – it remains a tight Lib Dem/Labour marginal, with the Greens also potentially in contention. Although fading last year, the Greens polled strongly in 2015, narrowly winning the seat on the old boundaries, and could perhaps make a come-back this time.

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Newnham sees little change with the new boundaries, retaining all its old area and adding just 9% of the old Castle ward. It remains a reasonably close Lib Dem/Labour contest, though with the Lib Dems ahead by a small margin.

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Petersfield is expanded significantly by the boundary changes, keeping all its previous voters and adding 34% of the old Trumpington ward, a Lib Dem stronghold. However, Labour have been doing well enough in Trumpington in recent years that this doesn’t do much to dilute their lead, and on the projection they retain a comfortable lead.

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The Queen Edith’s projection is particularly interesting. The old Queen Edith’s  was generally a Lib Dem stronghold, with the exception of a surprise Labour win in 2012, but on the new boundaries it looks like a much closer fight. The new Queen Edith’s seat includes 87% of the old Queen Edith’s, but adds 26% of the old Coleridge seat and 7% of the former Cherry Hinton – both being strong Labour areas. This is enough to erode the Lib Dem lead and put Queen Edith’s firmly into knife-edge marginal territory. Indeed the projection shows Labour slightly ahead on last year’s votes. Much will depend on how effective the rival party campaigns have been this year.

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The new Romsey includes all of the old Romsey’s boundary, and extends it some way to the south to include 34% of the old Coleridge ward. Coleridge has been a strong Labour area for some time, so this extends Labour’s lead in Romsey over the Lib Dems. Labour will be hoping for a comfortable win this year on the new boundaries.

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The new Trumpington seat is somewhat smaller than before, including just 66% of the old seat, plus 13% of the old Queen Edith’s. The projection is not very different from the previous Trumpington results, with the Lib Dems having mostly comfortable leads in recent years.

Overall, then, the projections show Labour leading in nine of the new seats on last year’s votes, with the Lib Dems ahead in just three – Trumpington, Newnham, and (by a whisker) Market. However, these projections definitely need to be taken with a pinch of salt – and a whole handful in the case of Castle. Nevertheless, they do indicate that there might be one or two surprises in store when the results are announced on Friday morning.

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One Response to What do the new boundaries mean for Cambridge’s local elections?

  1. Pingback: Thoughts on last week's local election results

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