Each answer resolves YES if, by 31 December of the stated year, legislation has received Royal Assent that directly mandates a new voting system for UK Parliament general elections, replacing First Past the Post. Otherwise it resolves NO when that date passes.

Qualifying voting systems:

Any of the following systems, or any hybrid system incorporating one of them:

∙ Single Transferable Vote (STV)

∙ Mixed Member Proportional / Additional Member System (MMP/AMS)

∙ Party-list proportional representation (open or closed list)

∙ Alternative Vote / Instant Runoff Voting (AV/IRV)

∙ AV+ (Alternative Vote Plus), as proposed by the Jenkins Commission

∙ Any mixed or parallel system that includes a proportional representation component, even if not fully compensatory

If a system not listed here is legislated, the market creator will determine whether it qualifies based on whether it uses proportional seat allocation, includes a proportional component, or allows voters to rank candidates in order of preference.

What counts:

∙ The legislation must directly mandate a change to the voting system — not merely establish a commission, promise a referendum, or enable a future vote on the question

∙ Must apply to UK Parliament general elections (not devolved parliaments, local elections, or by-elections)

∙ Must be a primary Act of Parliament (not secondary legislation or statutory instruments)

What doesn’t count:

∙ Legislation that only authorises or triggers a referendum on the voting system (e.g. the Parliamentary Voting System and Constituencies Act 2011 would not have counted)

∙ A commitment in a King’s Speech, manifesto, or coalition agreement

∙ Boundary or constituency changes that retain FPTP

If a referendum is involved: If an Act requires a confirmatory referendum before implementation, the legislation counts only once both the Act has received Royal Assent and the referendum has returned a YES result. Royal Assent alone is not sufficient in this case.

If the legislation delegates the decision — whether the choice of replacement system or the decision to change at all — to a commission, citizens’ assembly, or other body, it counts only once that body has made a final determination in favour of a qualifying system. If the delegation is binding, the date of that determination is the resolution date. If the delegation is advisory, the market resolves only when Parliament subsequently legislates to implement the recommendation.

Resolution source: legislation.gov.uk and the Parliamentary record (Hansard)​