For those of you who are asking the question above there is a web site that now demonstrates the effect AV voting reform would have on our elections.

They write:
The Voter Power Index AV referendum edition
In the run up to the 2010 general election, this website demonstrated that the vast majority of UK voters have little or no power to influence elections.
Now we have an opportunity to vote in the referendum to change the voting system from 'first past the post' to the 'alternative vote'.
How would AV affect the Voter Power Index? Using statistics from the New Economics Foundation (nef), we can demonstrate the increase in voter power that AV would bring.
Just type in your postcode and the web site will show you how the system would change if AV was adopted.