However some of the claims that have surfaced as a result have caused a bit of a stir. The University of Liverpool’s Professor Christopher Tuplin has a letter in this morning’s Times arguing that its political columnist Daniel Finkelstein is wrong to say that a second preference vote under AV is worth as much as a first preference.

 

Certainly some of these claims have trod a fine line between accuracy and error. Shadow Health Secretary John Healey, for example, cannot be said to be wrong to claim, as he did in a column for the Independent earlier this week, that: “Under AV people who back the likes of the BNP and UKIP would have several bites of the cherry, transferring their votes between candidates. People who back mainstream candidates would have their voices heard just once.”

Similarly, David Cameron is technically correct to say that: “Supporters of unpopular parties end up having their votes counted a number of times, potentially deciding the outcome of an election, while people who back more popular parties only get one vote.”

Voters whose first preference is eliminated in the early rounds of counting will indeed have their ballots counted more than once, unlike those who give their first preference vote to the eventual winner. But whilst it is counted more than once, it doesn’t count any more. Votes are transferred between preferences, they are not added to.

This is not a distinction that has always been upheld.

 

Last week the Times also carried a letter from a collection of historians opposing the switch to AV. In it, the academics noted that “for the first time since 1928 and the granting of universal suffrage, we face the possibility that one person’s casting ballot will be given greater weight than another.” This isn't the case.

Perhaps the best way to conceive of it is as a selection process involving the entire electorate in which all votes are allocated to a diminishing slate of candidates in each round of voting. Each round is therefore effectively a new ballot, and all the votes for the highest-ranked candidates remaining are given equal weight, regardless of the position that originally occupied on a voter’s ballot paper.