Some Analysis of the “Labour surge”

There’s been a lot of talk about the “Labour surge” so I’ve had a dig in the numbers to see what I can find. This is just a quick analysis and if I get time I will post more. In the meantime here’s what I’ve found.

Before we look at the Labour surge I want to look at the frequency distribution of the majorities for the two main parties in 2015 and 2017.

The two graphs below compare the 2015 and 2017 majorities. Note, to enable like-for-like comparisons of the trends the graphs only show the seats that were held in 2017 – they do not include the seats that were won or lost by each party in 2017. The graph uses histogram bins of 2,500.

01 lab freq dist

01 con freq dist

Three things strike me:

1. In 2017 Labour increased the majorities of safe seats and made them even safer. This can be seen by the dark red line shifting significantly to the right. Much of the Labour surge means Labour piling up extra votes where they are of little use other than to flatter the MP.

2. In 2017 the number of Labour seats with a majority of 2,500 or less decreased. These are what be classed as classic marginal seats. Form a Labour perspective this is good as they will have fewer marginals to defend.

3. Conversely for the Conservatives in 2017 the number of seats with majorities of of 2,500 or less increased. This means they have more marginals to defend. Again this is good for Labour.

Below is the 2017 comparative frequency distribution of the seats held by each party. You can see Labour has far more ultra safe seats where the votes have piled up.

01 both freq dist

Finally, turning to the biggest part of the surge, the graph below shows the 46 seats where Labour added on more than 10,000 extra votes. The colour coding shows which seats were Labour holds, Conservative holds and Labour gains. It shows quite convincingly that the biggest part of the Labour surge only (where Labour put on 10,000 or more votes) only helped Labour gain four seats out of the 46 seat where the biggest surges happened.

01 lab surge seats

Any future “mass Labour surge” needs to be make a bigger difference to maximise the seats gained rather than making already big majorities bigger. 


Ravi Subramanian is a full-time trade union official for UNISON; amateur maths, physics and technology geek; and now retired soul/funk/jazz/hip-hop DJ. So you can perhaps, unsurprisingly, expect posts on trade unions, politics, maths, science, technology, data and music. And maybe a few other things too.

Ravi blogs at: More Known Than Proven



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