Well, UK politics is possibly more diverse than it looks.
The Labour party is (Or was) socialist. The UK though is possibly at the core anti-socialist, so Labour realised they had to imitate the Conservative party (Centre right) to have a chance at a sniff of power. Deep down though, Labour are still socialist, they just are keeping that side a bit on the quiet really.
Politics in the UK is possibly polarised by habit - someone's father voted Labour, so the son does - that sort of thing. Small parties come and go - but no-one seems to take them seriously, so they don't really last long.
There is a third party called the Liberal Democrats - much more to the left of Labour nowadays. They however tend to pick up votes as a protest party, and indeed, in order to win by-elections, change their publicity literature to look like the Conservatives in the south, and Labour in the north - people tend not to notice they are doing this
Unsurprisingly, they are all for changing the system of electing politicians, which would - surprise surprise - cause a huge difference in the number of Liberal Democrat mp's elected (but of course, they say this isn't the reason they want to change it - yeah right
)
Politicians - who needs them. In a way, it's scary that the people in power are "career politicians" - people who have always wanted to be in politics, and don't therefore have experience of the real lives of real people.