Kinda. Bits of it are still in force[0], despite us not having a definitive text, but much of it was written to deal with contemporary political problems and was repudiated fairly quickly. It's more important as the start of a (semi-mythical) tradition of political liberty then as an ongoing source of constitutional law.
Even more excitingly, some of the documents we consider constitutional aren't even statutes. My favourite is a pseudonymous letter to The Times sent in 1950, which authoritatively established a constitutional convention for when the monarch can refuse his Prime Minister a dissolution of Parliament[1]. (The writer, 'Senex', was the King's private secretary Sir Alan Lascelles).
