United Kingdom Cabinet Office, Cabinet Manual
“ Instead, the constitutional order has evolved over time and continues to do so. It consists of various institutions, statutes, judicial decisions, principles and practices that are commonly understood as ‘constitutional’. The UK does not have a constitutional court to rule on the implications of a codified constitution, and the sovereignty of Parliament is therefore unrestrained by such a court (although see paragraph 6.41 for the jurisdiction of the UK Supreme Court over devolution matters.) ”
