If the Tories get half the votes, then they would deserve to be elected. They won't though.
PR is long overdue, we should be able to vote for the party that we want too. Not have to compromise and vote for a second choice.
However, we are where we are - we have FPTP, and that's why I'm offering to vote swop with anyone living in Hazel Grove or Cheadle, because I can vote Labour for you in the High Peak and together we can stop the Tories in both constituencies.