Electoral Systems


First Past the Post

Majoritarian constituency-based system

Used in:

  • Westminster 


  • Contains roughly equal constituencies which elect one member each which preserves the MP-Constituency link.
  • Produces a two-party dominant system which results in strong governments. (one coalition since 1945 and 2 minority governments produced directly from a General Election.)
  • MP's are directly accountable to their constituents who elected them.


  • Votes above majority for the winner in constituencies and votes for losers in constituencies are wasted reducing the incentive to turnout and the legitimacy of the government.
  • Difficult for smaller parties to break through the system. UKIP 4 million 1 seat.
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Supplementary Vote

Voters are only given two choices. A 1st choice and a 2nd choice. Every candidate is eliminated except for the top two. The eliminated candidates have their votes distributed to the remaining two candidates if possible. It's used in the London Mayoral Elections.


  • Broader support is needed to achieve a plurality of votes helping to ensure that a compromise is reached rather than extremes.
  • Retains MP-Constituency link.
  • Produces majority governments.
  • Accountable MP's


  • Wasted votes where they are non-transferrable (In 2016 more Lib Dem votes where wasted than transferred.)
  • Still forces tactical voting when it comes to the second choice as they may not be your true second choice.
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Single Transferable Vote

Proportional system used in the EU elections in the UK whereby voters rank candidates from 1st to last choice. Each candidate must surpass a quota of votes to be elected and the remainder of their votes are reallocated. If no-one passes the quota with seats still left to be allocated the lowest-ranked is removed and reallocated.


  • No wasted votes as all votes are reallocated.
  • Proportional to what the public wants
  • Helps smaller parties breakthrough so can better reflect public opinion with UKIP winning in 2014 and The Brexit Party winning in 2018


  • Multi-member constituencies lose MP-Constituency link
  • Takes a long time to count votes
  • Rarely produces a majority government.
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Addittional Member System

System used in the Scottish Parliamentary elections whereby there are two groups of elections. Voters cast two ballots one for the constituency they are in and one for the region they are in. A form of STV using the D'Honte formula is used for the regional list while FPTP is used for the constituency system.


  • Keeps the accountability of having one clear MP
  • More proportional of votes cast due to parties unrepresented from the constituency vote being represented in the regional vote.
  • Less wasted votes in the regional system


  • Does not produce majority governments.
  • Wasted votes in the constituency vote
  • Can lead to gridlock
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