The UK does not have a single codified document. It relies on a combination of statutory law, common law, and conventions.
Although fused in administration by the Judicature Acts of 1873-1875, the conceptual distinction between legal rules and equitable remedies remains. Law Express. English Legal System
Originally created to address the rigid, unfair outcomes of common law, principles of equity continue to operate and can provide unique remedies, such as injunctions. The UK does not have a single codified document