Alternative Vote (AV)
What is it?
The voter has the chance to rank the candidates in order of preference. The voter puts a '1' by their first choice a '2' by their second choice, and so on, until they no longer wish to express any further preferences.
Candidates are elected outright if they gain more than half of the first preference votes (absolute majority)
If not, the candidate who lost (the one with least first preferences) is eliminated and their votes are redistributed according to the second (or next available) preference marked on the ballot paper.
This process continues until one candidate has half of the votes and is elected.
Advantages
All MPs would have the support of a majority of their voters. Following the 2010 General Election, two thirds of the MPs elected lacked majority support, the highest figure in British political history.
It reduces the need for tactical voting. Electors can vote for their first-choice candidate without fear of wasting their vote.
Disadvantages
AV is not proportional representation and in certain electoral conditions, such as landslides, can produce a more disproportional result than First Past the Post (FPTP)
It penalises extremist/minority parties, who are unlikely to gain many second-preference votes. E.G. UKIP, Green Party, BNP
In close three-way races the “compromise” candidate could be defeated in the first round even though they may be more broadly acceptable to the electorate than the top two candidates.
A voting system that allows voters to rank candidates is prone to so-called 'Donkey voting', where voters vote for candidates in the order they appear on the ballot.

The referendum
In May 2011, there was a referendum held to ask the public if