New analysis produced exclusively for the Guardian reveals that different voting systems would return significantly different seat totals in the UK parliament, based on recent polling. The research, conducted by More in Common, suggests that proportional representation (PR) systems would likely reduce the number of seats for the leading party, creating a more finely balanced parliament.
Under current polling, the modelling indicates that no single party would achieve a majority under any of the proportional systems examined, including regional party list, single transferable vote (STV), and additional member system (AMS). This could lead to minority governments or progressive alliances of parties.
While the current first past the post (FPTP) system could leave Labour short of a majority with 250 seats, proportional systems would not give Labour such a boost. For example, the regional party list is estimated to give Labour 26% of seats from 26% of the vote, compared to 39% of seats from 26% of the vote under FPTP.
Smaller parties, such as the Green Party and the far-right Restore Britain party, are projected to be significant beneficiaries under PR systems. The Green Party, which would win only three seats under FPTP, could secure over 50 seats in all three PR systems modelled. Similarly, the Restore Britain party could surge to over 30 seats under PR, up from just one seat under FPTP.
Prime Minister Andy Burnham has announced a new national commission on electoral reform, a plan supported by over 100 Labour MPs and parties including the Liberal Democrats, Greens, SNP, and Plaid Cymru. Electoral reform has seen increased public support in recent years.