[nicoburns]

One might argue that the electoral system (FPTP) is a common denominator in both cases. Under another system, new parties might arise to replace to stale ideas of the old (on both the left and the right). Under FPTP, that's almost impossible to achieve.

It's a common refrain that people don't engage with politics because they feel disenfranchised. Which is perhaps unsurprising, because to a large extent they are!

[KaiserPro]

I think FPTP is a factor but not in the same way. The structure of the US system means that a president with a slim majority in one house can't do anything much. the UK has no such real problems.

In the UK you only have to win the commons (lower house) to run a government. the US you need both and the president.