AuroraSaab
Squire
Representation of minority parties is a direct result of PR. It happens in other countries and their political systems manage the consequences.
In the UK I don't think BNP members, or equivalent extremists from the left would have much influence. If however there had been ten UKIP members after 2010 or 15 they could have been much more difficult to deal with. More so in what might have been early years of a PR parliament where large numbers carry legacy baggage from FPTP and haven't the nous to form alliances or work across the gangway.
I can't recall the exact figure but I understand that, at their best showing, Ukip would have held the balance of power in parliament under a PR system (depending which one was used obviously). I agree with you about the UK system - the big parties don't work well together, and the electorate don't really go for tactical voting, or even loose coalitions once in power. We do seem to prefer an outright winner rather than a power share.
Fptp does keep extremists out but it would be nice if the main parties could look for things they do agree on and work at pushing those things through. There must be some common ground somewhere.