Under the system, better known and often referred to as simply ‘AV’, voters when entering the ballot booth would be asked to list candidates by order of preference.
When the votes are counted after polling closes, if no one scores 50% of the vote, the bottom-placed candidate is eliminated and the second choices listed on the ballots cast for that person are added to the totals obtained by the others.
The process is repeated until one candidate hits 50% of the votes cast, which will ensure that the overall most popular candidate is elected rather that an MP returned after only receiving a third (or less) of the vote.
Liberal Democrats demanded a date to be set for a referendum on the move to the AV system as a condition of creating a coalition that allowed the Conservatives to form a government.
"I'm hoping to make an announcement literally in a couple of days, next week," Lib Dem leader Mr Clegg said in answer to a question after making a speech in London today.
The Lib Dems hope a vote can be held as early as next May, but the referendum could indeed further expose strains in the coalition, with many of the coalition-partner Conservative Party have vocally expressed their opposition to changing from the first-past-the-post system.
Although AV falls short of the Liberal Democrat desire for a genuinely proportional voting system (Proportional Representation /PR), as I argued before on this blog the opportunity for a change – albeit halfway – should be welcomed.