Electoral system

• Types of Electoral system

  • First-past-the-post
  • Supplementary vote
  • Additional member system
  • Single transferable vote
• First-past-the-post


  • Typically produces single-party majority government (with the 2010-15 Parliament a notable exception)
  • Dominant party if the winning party enjoys a substantial winners' bonus or two-party if the majority is much smaller
• Supplementary vote

  • Single candidate becomes mayor
  • Two-party (because only two candidates can make it through to the second round of counting)
• Additional member system

  • Typically produces two-party coalition government or one-party minority government (with the 2012-16 majority Scottish government a notable exception)
  • Dominant party (the SNP has dominated Scottish Parliamentary elections) or three-party (smaller parties have participated in government, including the Liberal Democrats in Wales)
• Single transferable vote

  • Power sharing among several parties
  • Multi-party