Supplementary Vote and Other Majority Systems

This lesson examines majority and semi-proportional electoral systems, including the Supplementary Vote (SV) and the Alternative Vote (AV), and their relevance to UK politics.

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What Are Majority Systems?

Majority systems aim to ensure that the winning candidate has the support of a majority (more than 50%) of voters, unlike FPTP where a candidate can win with a mere plurality.

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The Supplementary Vote (SV)

How It Works

1. Voters indicate a first preference and a second preference
2. If a candidate wins more than 50% of first preferences, they are elected immediately
3. If no candidate achieves 50%, all candidates except the top two are eliminated
4. The second preferences of eliminated candidates' voters are redistributed between the top two
5. The candidate with the most votes after redistribution wins

Where It Was Used

• London mayoral elections (2000–2021)
• Other English mayoral elections (until 2022)
• The Conservative government abolished SV and replaced it with FPTP for mayoral elections in 2022 (Elections Act 2022)

Example: London Mayoral Elections