I can’t answer for America, but generally in democracies you get two and only two parties.
Your answer is both incredible specific to the UK and subtly incorrect. I don’t quite have the time to write a full rebuttal, but the more egregious of errors is this one:
The Liberals were the radicals, the party of industry and progress and free markets and who cares who it hurts as long as it’s the future.
One of the core tenets of liberalism is the harm principle. Sure progress is important but so is not harming anyone. Your post seems to equate only socialism with bringing good to British society, when that quite simply is just not true, and refutable. The Labour Party in the UK quite successfully adopted a lot of the items on the liberal agenda, such as gender equality.
The FPTP system is quite poisonous to the political debate in the UK as the natural tendency that only one of two parties can dominate and thus removes all nuance and creates toxic tribalism.