Recent elections have seen a lack of the strong majority government which have been the best reason for keeping our FPTP system. The current political climate points towards further fracturing of vote away from our two main parties. It is tempting to see this from a partisan perspective, that perspective needs to be considered if PR is going to get the support it needs to come to fruition and I will look at a few of the issues for Labour in a comment. As a party of power we have a duty of care for the electoral system as part of our democracy and if it is seen as unfit for purpose in the present and the likely future we have a responsibilty to reform it. Predicting the future may seem tenuous in politics, but if the reform is still considered healthy for a two party system then that duty remains.
Broader politics is changing, social media means people are publicly engaging in politics daily, and there is a plethora of political groups easily accessible. These themes of choice and access is being reflected in support for a greater number of political parties. When these are efffectively blocked from representing the electorate in parliament then supporters of those parties are disenfranchised.
With FPTP the ballot box is also used to 'keep the other lot out'. If in one's constituency the 'opposition' is not a party that you would support this also results in effectictive disenfranchisement. We also see governments with low vote shares returned when FPTP 'successfully' returns a stable majority. While FPTP may have been great when seen alongside the achievement of unversal sufferage it is unfit tor today's politics when we have access to more powerful communications systems than the postal office. This reform which unties the ballot from its constituency might open the way to other reforms in the future.
The Lib Dem proposal for a STV PR system was rejected in a referendum as it was seen as too complicated at the ballot box. This result should still be respected. I am proposing a variant of the party list system which is identical to our current system at the ballot box. Constituencies are grouped into 'areas' of five where votes are aggregated. A party's list is effectively made up of the candidates from the area's constituencies and the seats won via the DeHolt system are assigned to those candidates with the highest vote shares. The allocation system gives priority to giving partys with the weakest wins seats in constituencies where they have the highest representation. Most seatswill still have MPs who would have won a majority.
Most of the cultural trappings of our current system remain under this system while it give all the representational advantages of party list PR. Tactical voting is made redundant for those wishing to support any party viable in the area and gerrymandering is eradicated.
The attached file is a PDF of the the spreadsheet I have used to simulate the Scottish 2017 results under this system. I used Scotland as it is a relatively complicated electoral map due to the presence of the SNP such as we may expect to see in the future.
Out of interest an overview of seat results is SNP, from 36 to 22 Conservatives, 13 to 16 Labour, 6 to 15 Lib Dems 4 to 1. I will summarise and assess the model in a comment. I hope it is accessible having been converted from a spreadsheet.