One of the arguments, in fact the only real argument in favour of AV is that it is supposedly more representative of the electorate.
Come again. How does that work? Well it presupposes that how you vote demonstrates who you want to be elected, although that is clearly nonsense because your third or fourth selection may be elected using your vote, and they clearly aren't your first choice and probably not that representative of your opinion. Does that mean they can't represent you? Of course not, but there is something that we have forgotten.
At the last general election, only 29.65 million of the 45.54 registered voters actually voted. The other 16 million or so either were unable to vote or more likely couldn't be bothered to vote. Does that mean they don't consider themselves to be represented? Well, maybe or maybe not, but the chances are they still recognise their MP and since they couldn't be bothered to vote against any particular candidate, one can assume that most of them were quite happy to leave the decision to their fellow citizens (Oh, OK, subjects) so they can have no gripe at the outcome. Not voting is a free choice and one that we are entitled to exercise, but AV proponents choose not to respect that choice.
So with something around 35% of the electorate expressing no particular preference, any candidate with 16% of the electorate actually voting for them (about 24% of those actually voting) could reasonably claim that less than 50% of the electorate had voted against them. Or in other words, if we add the non-voters to the votes for the winner under FPTP, do we ever have a winner with more than 50% of the electorate voting against them?
And at the last election the answer is no. In 2010, one candidate only had 15% of his electorate vote for other candidates, the highest was 48.4% and the average was 34.5%. So when you really think about it, the only argument that AV ever had is a complete non-starter.