Eighty Years of Manifesto Rigor: Applying the Universal Civic Rigor Checklist (v2) to UK General Election Manifestos, 1945–2024

This RC version presents the first complete, gap‑free audit of every UK general election manifesto produced by Labour, the Conservatives, and the Liberal/Liberal Democrat tradition from 1945 to 2024. Using the Universal Civic Rigor Checklist v2, all 68 documents were read, verified against outside sources, and scored on ten criteria covering sourcing, numerical honesty, definitional stability, historical framing, disclosure, engagement with opposing arguments, tone, funding realism, independent corroboration, and causal honesty. The central finding is that all three major parties once sustained multi‑decade habits of engaging opposing arguments, and all three lost that capacity by the late 1990s or early 2000s. This version supersedes earlier releases by adding full Conservative coverage, correcting two scoring errors, and providing a machine‑readable dataset and codebook for independent replication. It is a refinement and consolidation of the previous version (“Two‑Party Complete Edition”), now extended to all three major parties. This version supersedes: “Eighty Years of Manifesto Rigor — Two‑Party Complete Edition” Relationship: isVersionOf Notes: Adds full Conservative coverage, corrects two scoring totals, expands dataset to 68 documents, and updates all findings accordingly.