A projection of how the election results would look if we used Additional Member System (AMS), like in Scotland and Wales.
| Party | AMS | FPTP | Seat change |
|---|---|---|---|
| Labour | 236 | 411 | +175 |
| LibDems | 77 | 71 | -6 |
| Green | 42 | 4 | -38 |
| SNP | 18 | 9 | -9 |
| Plaid Cymru | 4 | 4 | 0 |
| Reform | 94 | 5 | -89 |
| Conservative | 157 | 121 | -36 |
| Northern Ireland | 18 | 18 | 0 |
| Other | 4 | 6 | +2 |
The Electoral Reform Society also favours STV, they probably chose AMS here as modeling it from FPTP isn’t complete guess work.
I actually wrote my thesis on analysing the 2019 election results and extrapolating vote choices for other systems and seeing how that would affect the balance of power in the UK .
Presumably part of that was trying to account for the lack of preference data?
If you spend a long time scrounging through different polls and opinion surveys, you can find quite a bit to patchwork together.
Which is fair in an academic sense, but it scares the willies out of people who don’t understand it’s one of the least likely systems we’d use and how important the choice is.