Proportional representation: The pros and cons
Is a radical reform of the voting system key to healing Britain's political divisions?
As the nation reels from the impact of the vote to leave the EU, there have been calls for a fundamental shake-up of the UK's political system.
With only a few percentage points deciding the future of the country in last week's referendum, is a more representative system needed to ensure that government power is not divided on a similar all-or-nothing basis?
An increased interest in proportional representation (PR) would be more good news for Liberal Democrats, who are already enjoying a membership boost following their promise to block the UK's withdrawal from the EU.
The Lib Dems have long campaigned for parliament to adopt PR to give minority parties such as themselves, the Green Party and Ukip a bigger voice in government.
So how does the system work and what are the arguments for and against?
A new system could take two forms: alternative vote (AV) - which is not proportional, but is likely to increase the representation of small parties - or single transferable vote (STV), which is truly proportional.
In both systems, voters rank the candidates by preference. AV takes into account the first choices, then second and third preferences until a candidate reaches more than 50 per cent of the vote, when they are declared the winner.
To be elected under STV, explains, Electoral Reform, "candidates need to reach a set share of the votes, determined by the number of positions to be filled" and the number of voters.
Each vote can be transferred from the first preference to the second preference, "so if your preferred candidate has no chance of being elected or has enough votes already, your vote is transferred to your second choice candidate in accordance with your instructions".
Adopting STV would mean a massive overhaul of the current system, as there would no longer be one politician representing each constituency. There would also have to be far fewer and much larger electoral constituencies to send proportional groups of MPs to Westminster.
The case for proportional representation
Under the current "first past the post" (FPTP) system, power tends to end up with one party (or, occasionally, a coalition) no matter how small its majority. MPs have been elected despite 75 per cent of their constituency voting against them.
A more proportional system would give minority parties and independent candidates a better chance of getting into parliament, proponents argue, and introduce different voices to our national political life.
People supporting Labour in a traditional Conservative stronghold, or vice versa, would not be "wasting" their vote. This would mean that the parties would have to appeal to their core supporters, rather than the 200,000 or so swing voters in marginal seats.
There could be a higher turnout at the polls under PR. A study into voting patterns in New Zealand showed a "modest increase" in turnout after its switch from FPTP to PR in 1996, as well as a more positive overall attitude about the power of voting.
Some form of PR is used by the majority of the world's leading democracies. Only a few countries, including the UK, the US, India, Canada and France, still have elections that are decided by plurality voting systems.
As PR seldom results in one party holding an absolute majority, it requires governments to compromise and build consensus, meaning that – in theory, at least – stable, centrist policies will carry the day.
The case against
PR allows extremist parties to gain a foothold in national life, say those in favour of keeping the current system. If the last UK general election had been held under a PR system, Ukip would have been the third-largest party in parliament, with 83 seats instead of one. Good news for its supporters, but worrying for those who fear its appeal comes hand-in-hand with a resurgence of xenophobia and nationalism.
Under FPTP, MPs serve the constituency they campaign in so are more inclined to tackle important local issues. Under PR, electoral constituencies would have to be much bigger, possibly leading to local issues being lost in the crowd.
Nor is compromise always ideal. Neither the trade union reforms that Margaret Thatcher pushed through nor Tony Blair's raft of improvements to public services could have been carried through without a strong governing majority.
The coalition governments that PR tends to produce are often weak and indecisive, say its detractors. Italy, which has such a system, has had to dissolve its parliament eight times in the last 40 years. Plus, politicians have to actually form a coalition – following the 2010 general election in Belgium, negotiations went on for a record-breaking 541 days, leaving the country essentially ungoverned for almost 18 months.