I'd argue that the UK has always had a 2-party system, and if anything the US adopted it from us. The Lab/Con split goes back to ~1910, prior to which we had th

I'd argue that the UK has always had a 2-party system, and if anything the US adopted it from us. The Lab/Con split goes back to ~1910, prior to which we had the Tory/Liberal split going back to ~1850, prior to which we had a Tory/Whig split going back to ~1780, prior to which the political system was very different.