Does the UK have a constitution? Does it matter?

A Constitution can be defined as the rules and practices that determine the composition and functions of the organs of central and local government in a state and regulate the relationship between the individual and the state. It is the document or documents embodying the most important laws. Thus we can say that in general a constitution allocates authority within a country, by defining the powers of government and the rights of the citizen, Most states have a written constitution, one of the fundamental provisions of which is that is can itself be amended only in accordance with a special procedure.  Does the United Kingdom have one?…(short extract)