Not strictly true: The government is the party that wins the most
constituencies.
And they typically have only about 40% of the actual vote.
Well yes quite possibly. Overall FPTP is a system that has served us well, it's not perfect but in my opinion a damned sight better than PR.
The advantages of a PR electoral systemMoving to proportional representation (PR) in the UK may offer would give minority parties and independent candidates a better chance of winning seats in Parliament.
The current First Past the Post electoral system is considered unrepresentative, as candidates can be elected with a very small share of the votes while all other votes cast in the constituency are wasted.
PR ensures that the parties would have to appeal to their core supporters, rather than a small number of so called ‘swing voters’ in marginal seats.
It could be argued that PR delivers fairer treatment of minority parties and independent candidates
Under PR fewer votes are ‘wasted’ as more people’s preferences are taken into account
PR potentially offers greater and more-representative choice for voters.
PR may encourage turn-out and reduce apathy.
PR rarely produces an absolute majority for one party, however, it could be argued that PR ensures greater continuity of government and requires greater consensus in policy-making.
The disadvantages of a PR electoral systemUnder FPTP, MPs serve the constituency they campaign in. This makes them more inclined to tackle important local issues.
PR can potentially provide a route for extremists to force their way into the political mainstream: under a FPTP electoral system this would be unlikely to happen.
Some would say that PR produces ‘weak’ coalition governments rather than ‘strong’ majority governments, which arguably can lead to indecision, compromise and even legislative paralysis.
PR can also reduce accountability to voters, as an ousted party of government can retain office by finding new coalition partners after an election.
The adoption of PR list systems weakens the link between the elected representative and his or her constituency.
The greater complexity and choice that PR allows can put voters off voting, by requiring them to have a greater knowledge of individual and party positions.
uk-engage.org/2013/08/what-are-the-advantages-and-disadvantages-of-using-a-proportional-representation-pr-electoral-system/