Proportional Representation (PR) is one of the most widely-used systems worldwide, supported by many groups as a replacement for the existing First-Past-the-Post electoral system on the basis of its ability to accurately represent the wishes of the entire electorate. The table and graph illustrates the results of an election conducted under Proportional Representation1

Year Conservative Labor Liberal Democrats Others
2015 249 206 53 32 SNP, 85 UKIP, 25 Green
2010 266 214 170 None Pass threshold
2005 234 254 158 None Pass threshold
2001 230 296 133 None Pass threshold
1997 223 314 122 None Pass threshold
1992 290 238 123 None Pass threshold
1987 288 209 153 None Pass threshold
1983 289 188 173 None Pass threshold
1979 295 248 92 None Pass threshold


Several important trends to note:

  1. No party seems to be able to obtain a majority in a PR system. This is because most votes in UK elections are divided among the three major parties, and it is extraordinarily hard for one of these parties to break through and obtain a majority.
  2. Minor parties, such as the SNP, Greens and UKIP only manage to gain representation in the 2015 election. This is because prior to 2015, none of these parties managed to gain over 3.25% of the vote that is required to break into parliament under this form of PR. However, it is important to note that this model does not keep into account the different ways people vote in PR, and it is likely that with a more fragmented party system in PR, many more minor parties gain representation.Capture
  3. The Liberal Democrats appear to consistently gain seats with PR – they are almost always underrepresented compared with other parties. When compared to FPTP, the Conservatives lose out most of the time, and gain slightly only in the period of Labor dominance from 1997-2005. Labor seems to consistently lose out in a PR system.Capture2
  4. When compared with the results under an Alternative Vote (AV) system, it appears that the Liberal Democrats maintain their gains, whilst Labor and the Conservatives lose out in the periods of time when they are the first party in parliament.
  5. In 2015 and 2010, AV seems to have benefited both the Conservatives and Labor compared to other forms of electoral reform, which might have been why they were so willing to propose it to the Liberal Democrats when attempting to form a coalition.
  6. It is quite confusing why the Liberal Democrats might have preferred AV over PR. However, it might be related to the fact that over time, voters would vote differently in an AV system.
  7. Ultimately, the probability of implementing an Israeli-style PR system is low: with the regional parties all but eliminated in this system, another form of PR (STV, MMP or low-cutoff) appears to be a lot more likely choice.

1. In this case, we use the Israeli method of proportional representation, with a 3.25% cutoff. This model does not keep into account the different ways people vote in PR.