7 alternative parliaments: what if the UK used PR voting?

The UK currently uses the first-past-the-post voting system, but what if it switched to a fairer system.

First-past-the-post accentuates the support of the two largest parties while weakening the ability for minor parties to get seats. Just look to UKIP in 2015 and the SDP in 1983 to see how smaller parties are punished. But what if the UK used a more proportional system? There are countless options from the Additional Member System, to the Single Transferable Vote as well as full-blown party-list PR.

Let’s say the UK introduced a purely proportional electoral system ahead of the 1992 election where votes equalled seats. What would have happened?


At this election Major's Conservatives won over 14 million votes, the highest total of any party in British political history.

The Conservatives won 41.9% of the vote, which would deprive them of a majority in a proportional parliament. Labour won 34.4% while the Lib Dems won 17.8%. The SNP won 1.9% of the vote.

In a 650-member proportional parliament, the results would be as follows:

  • Conservatives = 272 seats
  • Labour = 223 seats
  • Lib Dems = 116 seats
  • SNP = 12 seats


Such an outcome could realistically lead to one of four options: a Conservative minority with Lib Dem support, a Conservative-Lib Dem coalition, a Labour minority with Lib Dem support or a Lib-Lab coalition. At this election, the Liberal Democrats would have been the all-powerful king-makers.

1997 election

In reality, Blair won a landslide, but a shift to PR would have ensured that New Labour’s share of the seats in parliament equalled its share of the vote.

In a 650-seat parliament:

  • Labour = 281
  • Conservatives = 200
  • Lib Dems = 109
  • Referendum = 17
  • SNP = 13 seats

The most likely outcome would have been a Labour minority government with Lib Dem support or Lib-Lab coalition.

2001 election

Very few seats changed hands at this election, but how would things have fared under a proportional system?


  • Labour = 265
  • Conservatives = 207
  • Lib Dems = 119
  • SNP = 12 seats
  • UKIP = 10 seats


The likely outcome would have been the continuation of some sort of Lib-Lab arrangement.


At this election, Tony Blair secured a third term, winning an overall majority with a strikingly low share of the vote. New Labour won just 35.2% of available votes, less than Cameron’s Conservatives in 2010 and May’s Conservatives in 2017, but they still managed to secure a big majority.

What would have happened in a PR election?


  • Labour = 228
  • Conservative = 211
  • Lib Dems = 143
  • UKIP = 14
  • SNP = 10


Under first-past-the-post, Labour secured an historic third term, but a PR election could have seen an early end to Blair. Together, the Lib Dems and Labour could have continued their agreement from the 1997 and 2001 elections, but with the Lib Dems stronger than ever before and Labour significantly weakened, the dynamics of a new coalition would have been significantly altered.

On top of that, the electoral maths adds up in a way that could have allowed Conservative leader Michael Howard to become prime minister. If the Tories gave enough to the Lib Dems, they could woo them into supporting them rather than Labour. A Conservative-Lib Dem coalition would have had a combined total of 354 seats.

2010 election

In reality, this election led to a hung parliament, as would be the case in a proportionally representative parliament.


  • Conservatives = 235
  • Labour = 189
  • Lib Dems = 150


Such a result would have made the Liberal Democrats kingmakers once again, giving them the power to place either David Cameron or Gordon Brown into Number 10.

2015 election

At this election, Cameron won a surprise majority, but what would have happened had it been held under PR?


  • Conservatives = 239
  • Labour = 198
  • UKIP = 82
  • Lib Dems = 51
  • SNP = 31
  • Greens = 25
  • Plaid Cyrmu = 4


Had the 2015 election been held under a fully proportional voting system, some interesting coalitions and deals could have been formed.

Possible outcomes:


  • Conservative-UKIP minority coalition, with support from Northern Irish parties
  • Conservative-Lib Dems, with UKIP support for EU referendum
  • A progressive alliance led by Labour would have struggled to make it to 325 seats and would have been prone to instability.


A German-style grand coalition between Labour and the Conservatives would have been the only combination of two parties to make a majority.

2017 election

Theresa May’s gamble did not pay off and she turned her majority into a minority, but what would have happened had it been a proportional election?

The Conservatives would have gained seats rather than lost them due to the party’s increase in share of the vote. Labour too would make gains, just as it did in reality.


  • Conservatives = 275
  • Labour = 260
  • Lib Dems = 48
  • SNP = 20
  • UKIP = 12
  • Greens = 10


Had 2017 been conducted under PR, Jeremy Corbyn could have emerged as prime minister. A deal between Labour, the Lib Dems and the SNP would put the “left-alliance” over the magic number of 325. Support from the Greens could also boost this progressive pact’s stance in the Commons.

On the other hand, a Conservative-Lib Dem deal would fall short of the required 325, but in reality would be a working majority if Sinn Fein MPs did not take their seats.

Once again, the Liberal Democrats would be the king-makers.


This is just a thought exercise. In reality a change in electoral system in 1992 would undoubtedly have had an effect on the wider party system across the UK so subsequent elections would not have played out the way they had. For instance, had the Referendum party entered the House of Commons in 1997, they could have built on top of that success. Or had the Lib Dems gone into coalition with the Tories much earlier than they did in reality, their support would likely have plummeted well before the 2010 election.

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