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

Year	Winner	First Round	After Redistribution
2016	Sadiq Khan (Lab)	44.2%	56.8%
2021	Sadiq Khan (Lab)	40.0%	55.2%

In both cases, Khan did not win outright in the first round but secured a majority after second preference redistribution.

Advantages of SV

Advantage	Explanation
Majority support	The winner usually has broader support than under FPTP
Simple	Voters make only two choices
Reduces tactical voting	Voters can express a genuine first preference and a strategic second preference
Single representative	Like FPTP, produces one clear winner for the position

Disadvantages of SV

Disadvantage	Explanation
Not fully proportional	Still a majoritarian system; does not produce proportional representation
Limited preferences	Voters can only express two preferences (unlike AV, where they can rank all candidates)
Spoiled ballots	Some voters may not understand the two-preference system
Still favours larger parties	The top two candidates are almost always from the major parties

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The Alternative Vote (AV)

AV is a preferential majority system that allows voters to rank all candidates.

How It Works

1. Voters rank candidates in order of preference (1, 2, 3, etc.)
2. If a candidate wins more than 50% of first preferences, they are elected
3. If not, the candidate with the fewest votes is eliminated and their votes are redistributed according to voters' next preferences
4. This process repeats until one candidate has more than 50%

The 2011 AV Referendum

In 2011, the UK held a referendum on whether to adopt AV for general elections (a condition of the Conservative-Lib Dem coalition agreement).

Result	Percentage
No	67.9%
Yes	32.1%
Turnout	42.2%

The decisive rejection of AV set back the cause of electoral reform significantly.

Why AV was rejected:

• The Conservative Party and much of the media campaigned vigorously against it
• Public understanding of AV was limited
• The campaign was poorly run by the Yes side
• Some argued AV was not proportional enough (the Lib Dems really wanted STV)
• Low turnout suggested limited public interest in the issue

Advantages of AV