Despite receiving 7.4 percent of the votes for the Liberal Party, the UK’s electoral system is responsible for awarding them only 1.8 percent of the seats. For continental Europeans the United Kingdom’s electoral system seems to have some odd characteristics. In general, candidates win their constituency on a regular basis lacking a majority of votes, and the parliamentary share of seats often is at odds with the overall popular vote. Those circumstances and the recent election provide a good opportunity to examine the UK’s electoral system.
Let’s take a look at the consequences for parties after the 2017 general election. For that purpose I have included a graph that shows the difference between vote share and seat share.
The green bar represents a higher percentage of seats than votes, the red bar represents fewer seats than votes. Take for example the election result for the Conservative party. In 2017 32,204,141 people have cast their vote. Out of those 32.2 million people 13.65 million have voted for the Conservative party. Those 13.65 million people represent 42.38 percent of the electorate. But the Conservative Party has won 318 out of 650 seats in the 2017 general election. These 318 seats are in fact 48.92 percent of the total 650 seats. Therefore, they got 6.52 percent more seats than votes they received. So what is the reason for this difference and isn’t it a bit unfair to get a greater percentage of seats than actual votes? To answer these questions, we take a look at the electoral formula.
In general, the electoral formula determines how votes are transferred into seats. The formula for the UK’s parliament is pretty straightforward. Their parliament consists of 650 seats. Accordingly, there are 650 constituencies in the UK. To win a seat a candidate has to get a plurality of votes in his constituency. A plurality of votes simply means more votes than any other candidate. Take for example Theresa May’s constituency of Maidenhead, where she achieved 37,718 votes in the 2017 election. In the unlikely event that Lord Buckethead would have received 37,719 instead of the 249 he actually got, he would be a member of parliament instead of Theresa May. Hence, this plurality system is pretty simple but can lead to situations, where candidates win their constituency without a majority of votes. This is especially true when more viable candidates enter the race for the same constituency.
You might think that a system that produces disproportional results is bad and parties should get an equal amount of seats compared to their votes. But you should consider that even in systems that aim to produce proportional results seat share and vote share rarely match. In addition, minorities that are regionally concentrated tend to be better off with the plurality system.