Randomised voting.

Keep the constituencies exactly as they are, and each election everyone votes the way they do now.

Then instead of counting the votes, we shuffle them and pick a random vote and do what it says.

In aggregate this is proportional across the country, and also means every voter remains important in the constituency, you never know if the person you piss off today might personally vote you out tomorrow.

It also eliminates career politicians. Even in a safe seat you probably won’t win three terms.

It’ll never get used anywhere but it’s fun to think about.