Cataloguing Convention: Why 2026 Should Publish Britain’s Constitutional Rulebook

Britain does not have a written constitution, but it does have a constitutional rulebook. The problem is that the rulebook is scattered across the Cabinet Manual, the Ministerial Code, parliamentary standing orders, prerogative instruments, devolution concordats and conventions that exist mainly in precedent and memory. That dispersal is not merely untidy. It makes accountability harder for Parliament, opaque for citizens and unnecessarily dependent on the private knowledge of officials and ministers. The answer is not a written constitution. It is a public constitutional register: a statute book of the unwritten rules.

What would be published

A register would not seek to codify the constitution in a single document with entrenched status. It would catalogue the materials that already guide constitutional practice. That means conventions such as ministerial responsibility, collective responsibility, the caretaker convention and the Sewel convention. It means prerogative powers: treaty ratification, the deployment of armed forces, the dissolution of Parliament, the appointment of ministers and the organisation of the civil service. It means ministerial guidance and codes that have practical constitutional effect, from the Ministerial Code to the Cabinet Manual and the various devolution concordats. Each entry would record its source, its status, its known exceptions and the date of its last review. It would be searchable, version-controlled and public.

Why this is a conservative reform

The centre-right case for such a register is not that it transfers power to judges. It is that it transfers information to the public. Conservatives have long argued that discretion should be bounded by rules and that authority should be accountable for how it uses them. A public register does exactly that. It makes it harder for ministers to invent a convention when it suits them and harder for officials to rely on unwritten understandings that Parliament cannot see. It also reduces the scope for judicial creativity. If the courts are asked to identify a convention or a prerogative power, they should be able to consult a public record rather than infer the constitution from whichever precedent is most convenient to the parties.

That is why the register should be declaratory, not operative. It should not create new rights, new causes of action or a new power of judicial review. It should not entrench its contents against future legislation. It should not turn the courts into a constitutional court with authority to strike down statutes. Its purpose is evidence, not supremacy. A statute could place a duty on the Cabinet Office to publish and maintain the register, with an annual statement to Parliament and a joint committee to review its accuracy. But the legal effect of an entry would be to record what the rule is, not to change it.

The objections from both sides

Critics on the right will say that any attempt to write down conventions is the thin end of a written constitution. They are right to be cautious, but the objection proves too much. The courts already recognise conventions; the Cabinet Manual already describes them; the government already publishes some of them. A register would make that process more transparent, not more judicial. It would also make it harder for a future government to quietly abandon a convention without public explanation. That is a conservative gain, not a legalistic one.

Critics on the left will say that a register might freeze conventions in a form that favours the executive or entrenches arrangements that should evolve. That is a fair warning, which is why the register should be revisable by ordinary ministerial statement and parliamentary debate, not by constitutional amendment. It should record disputes as well as settled practice. Where the parties disagree about whether a convention exists, the register should say so rather than pretend to a certainty that the constitution does not possess. Transparency is not the same as rigidity.

How to do it without a written constitution

A centre-right government could implement this without a grand constitutional convention. It could begin with an audit of existing published guidance, followed by a draft register laid before Parliament for scrutiny. The Joint Committee on the Constitution and the Public Administration and Constitutional Affairs Committee could take evidence. Devolution concordats would be included only with the consent of the devolved administrations. The register would be reviewed annually, with a duty to explain any omission or change. None of this requires a new bill of rights, a new supreme court or a new constitutional settlement. It requires the political will to publish what is already known.

The constitution is not made weaker by being better understood. It is made stronger. A public register would not give Britain a written constitution, but it would give Parliament and the public a clearer view of the rules by which they are governed. For a centre-right government that believes in accountability, that should be an easy case to make.