FullFact has an article on AV and also links to an interesting paper by The Constitution Society, the latter paper of which I was unaware until today.
Some interesting facts emerge, again of which I was unaware; namely that as each round of counting proceeds:
"The more rounds of counting required to elect a winning candidate, the greater the chance that votes will cease to be counted as they had not expressed a preference for any of the candidates remaining in the election. The number of votes required to win the contest therefore drops." (FullFact)
"The explanatory note from the Bill states that candidates must achieve more than 50% of the votes in the count - either at the initial counting stage or, if necessary, at a further counting stage - in order to be elected. The Bill therefore anticipates that the total number of votes counted in each round will be diminishing, so that the winner in final round need not necessarily have polled more than 50% of all votes cast in the election." (The Constitution Society)
It can also be seen that some voters 2nd preferences are not counted because their first preference has been eliminated in the previous round. The point that the winner in the final round need not necessarily have polled more than 50% of all votes cast in the election is borne out by the findings of the Jenkin Commission and also made in point 4.2 of the Constitution Society paper:
"Nor, in the ‘optional preference’ proposed for the UK, does the winning candidate necessarily have an outright majority of the total vote (i.e. of the total number of people who voted). In Australia, where the AV system is used for House of Representatives elections, voting is compulsory and voters are thus required to allocate a preference to every candidate on the ballot. As a consequence, the winning candidate does always achieve an outright majority of the total vote."
All in all it really does seem that AV is not the system it is being presented as, neither does it seem to be 'fair' when some 2nd preference votes are discounted. It is also patently obvious that the argument promoted by Yes2AV that all winning candidates will have received 50% plus 1,is not correct. Neither, it has to be said, is it "one man, one vote". Ed Miliband demonstrates every politicians ability to be economical with the truth when he said:
"But it would help to restore the balance of power in favour of voters because it would force all MPs to earn the majority of votes."Finally - and my apologies if I am being a bore - I can but repeat my earlier observation that if the voting system is to be changed then it should be up to the electorate to select that system which they prefer from all available options - and not have a choice thrust upon them by the political elite.