First Past the Post
The voting system fails on measures that are not in dispute.
The place the present system fails most measurably is the ballot box. First Past the Post was built for a two-party country that no longer exists; run on a multi-party one, it distorts the result in ways anyone can count. These are the numbers, each with a source.
The Gallagher index score for the 2019 general election. Ireland's STV scored 3.1, Germany's MMP 1.8. Above 10 is treated as severe distortion between votes cast and seats won.
Source: Gallagher index, published results.11.6% of votes returned 1.7% of seats, a roughly sevenfold gap between support and representation. Single-member districts compress smaller parties hardest.
Source: 2019 general election result.Just over a third of votes cast translated into a working Commons majority. A government's mandate and the support behind it have come apart.
Source: 2024 general election result.The estimated share who rank a compromise candidate above their genuine first choice, because backing whom they actually want would waste the vote. The system corrupts the signal it is meant to read.
Source: British Election Study; comparative surveys.Seven ways it fails, all at once
Part III of the Rulebook sets out the diagnosis in full. In short, First Past the Post fails on seven measurable counts at the same time:
- Representation. Seat share diverges wildly from vote share, 56% of the seats on 44% of the vote in 2019; a working Commons majority on roughly a third of it in 2024.
- Vote-weight inequality. A vote in a safe seat is worth almost nothing; a handful of marginal seats decide the entire election.
- Tactical coercion. Millions vote against their real preference to keep someone out. The system corrupts the very signal it exists to read.
- A wall against newcomers. The Liberal Democrats took 11.6% of the vote in 2019 and 1.7% of the seats. Independents and smaller parties are crushed by the winner-takes-all district.
- Gaming. Under winner-takes-all, boundaries and vote-management reward whoever already holds the seat.
- Weak auditability. Opaque, hard-to-verify totals, with no end-to-end check an ordinary citizen can run for themselves.
- Legitimacy erosion. The cumulative effect is falling turnout and falling trust, the slow failure that precedes the fast one.
None of this is inevitable, it is fixable, and other countries have fixed it. Ireland has run the single transferable vote since 1921 and scores 3.1 on the same distortion index where the UK scores 11.8. Germany scores 1.8. New Zealand abandoned First Past the Post and cut its score from about 12 to under 4.
Fourteen systems, scored against eight weighted criteria
BIG's founding work scored every major electoral system on published, weighted criteria rather than on which party each would favour. The shortened table below shows where the main options land; the full matrix and method are in Part III of the Rulebook.
| System | Proportionality | Tactical resistance | Gaming resistance | Total /100 |
|---|---|---|---|---|
| STV+ Recommended | 9 | 8 | 8 | 81 |
| MMP, New Zealand model | 8 | 7 | 7 | 76 |
| Open List PR | 8 | 7 | 7 | 71 |
| AV / Instant-Runoff | 5 | 6 | 7 | 62 |
| First Past the Post UK today | 2 | 3 | 3 | 39 |
STV+ is not put forward as perfect. It does not abolish tactical voting, only reduces it; it does not guarantee stable coalitions; and it asks more of the count than First Past the Post does. It wins because, against the criteria above, it beats the alternatives, and because Ireland has run STV nationally since 1921 and Scotland since 2007, the evidence for it is observed rather than projected.