Which to me, begs the question, how would people vote under PR. My initial reaction is that as seen elsewhere minor parties would benefit.
2010 would have seen an even further rise of Nationalist parties, and maybe even a breaking of the Lab/Con 1-2?
2015 - almost certainly Nigel Farage as...
Obviously people would vote differently under PR, but this is the results for a UK wide D'Hondt PR system. IMO you'd need a Federal / regional system like the EU elections for the UK
2017:
Conservative (42.72%): 280
Labour (40.34%): 264
Lib Dems (7.43%): 48
SNP (3.06%): 20
UKIP (1.86%): 12...