In the spirit of your most thorough pedantry, I thought I'd correct your correction to say that OP is right, David Cameron didn't win an election, he won a seat as an MP.
None of the parties achieved the 326 seats required for an overall majority under the First Past the Post system. The Conservatives won the largest number of votes and seats but under FPTP rules were 20 seats short.
Do you have a reference for that? Is Australia trying to give undue influence to fringe parties? Are the conservatives trying to promote fringe candidates?