It's fair as an electoral system can be. More importantly, it is honest, open, stable, practical, and people understand it. The alternative systems might seem mathematically fairer, but they are unstable, secretive, and actually take power from the public and deliver it to party bosses.
The electoral system that the UK uses for Parliamentary and local Government systems is known as First Past the Post (FPTP). It is the most common system for elections in the world, used by 68 countries
FPTP has 5 great strengths that other systems do not have: 1) It makes politics simple. It provides a clear cut choice for voters between two broadly based parties. 2) The public know what (and who) they are voting for 3) after the election the government has a clear mandate and a clear programme that it can start on immediately 4) If the government fails to deliver, it will be voted out and replaced by the opposition. 5) It limits the power of party managers. Each candidate is named on the ballot paper and holds their seat in a personal capacity, representing a defined geographical region. They cannot be removed by the party, only by the people.
This is a sensible system and this is what we are used to. It’s not perfect, and its not always “fair”, but it works, and it keeps our politics relatively honest, pretty clean, and transparent, and generates a high level of political debate and voter turnout (69% turnout in 2017)
It’s worth remembering that in 2011 the British people voted by 68% to reject a Lib-Dem inspired change to our electoral system, called the “Alternative Vote”. And yet, just like over Brexit, the Lib-Dems choose to ignore the voice of the public. It’s time for the Lib-Dems to listen; because the British people have already spoken.