2010 General Election under Proportional Representation
We will take a brief look at how the 2010 general election would have looked if it were held under a proportional representation (PR) system. For simplicity we will:
1. Exclude Northern Ireland. Politics in Northern Ireland is different to that in Great Britain. Neither the Conservatives, Labour nor the Liberal Democrats are big players there. Furthermore, tactical voting is common and parties often stand down in favour of other parties or independent candidates. Therefore we will consider 650 - 18 = 632 seats to be distributed throughout Great Britain.
2. Set the threshold for entering parliament at 0.5%. Essentially this means that a party must achieve 0.5% of the overall vote to win any seats. We will discard any votes cast for parties that score under the threshold.
3. Allocate seats on a Great Britain wide basis. We will calculate the seat count of a party by multiplying its proportion of the non-discarded votes by 632 seats and round to the nearest integer.
4. Assume that no tactical voting occurred in the 2010 general election. Of course this assumption is absurd as tactical voting no doubt did occur. Many marginal constituencies tend to turn into two horse races which causes the parties who polled third place or worse in the previous general election to be squeezed out of the picture.
2010 General Election under PR
237 (-69) Conservatives
191 (-67) Labour
151 (+94) Liberal Democrats
20 (+20) UKIP
12 (+12) BNP
11 (+5) SNP
6 (+5) Green
4 (+1) Plaid Cymru
(changes from the 2010 general election).
Notice how changing to PR severely disadvantages the Conservatives and Labour with the Liberal Democrats being the main beneficiaries. Unlike the actual 2010 general election, the minor parties would have made a breakthrough, namely UKIP, the BNP, the Green Party and the SNP. No single party would have had an overall majority. Only three possible two party majority coalitions would have been possible, namely
1. Conservative+Liberal Democrat (majority 126)
2. Labour+Liberal Democrat (majority 34)
3. Labour+Conservative (majority 206).