A hypothetical codified British constitution

If you could pass one law that could never be altered, what would it be?

A codified British constitution would entrench rights, set spending floors for defence and education, and define the devolved institutions more clearly.

Rather than choose a narrow statute, the answer uses the hypothetical power to write a codified British constitution. The proposed constitution would entrench privacy and human-rights protections behind several institutional locks. Defence and education would each receive a minimum of three percent of GDP because both are treated as foundations of national capacity. Constitutional amendment would require agreement across the Supreme Court and every parliamentary chamber rather than a single temporary majority. The proposal also defines the roles of the devolved institutions and creates an English parliament on a more equal basis. This personal counterfactual bundles spending rules, rights, devolution, and amendment procedures into one institutional design.