First Past The Post (FPTP) is a very crude dispute resolution system to choose and change governments without resort to violence. Although it’s considerably better than coup, assassination or revolution, it could be much better. Most European democracies have better systems, but the UK has been left behind except that we have made a little progress with the devolved bodies and some other elections.
In a real democracy, Parliament would be a small but accurate reflection of the political views of the voters and the Government would reflect the political views of the majority of voters. FPTP does not achieve that. Without PR, the UK is only half a democracy – a demi-ocracy.
STV is the best kind of PR for many reasons, not least because it increases voter – not party – power and it can provide proportionality not only between parties but also between other groupings,such as Brexiters and Remainers.