Granted, Habeus Corpus existed prior to Magna Carta, and that document did not initially provide any protections to anyone other than the very powerful, but Magna Carta has provided a powerful deterrent against arbitrary detention of civilians for nearly 800 years.
So, well done to New Labour. The House Of Commons passed a motion to extend detention without charge to 42 days earlier in the week. Who needs centuries of a basic human right to continue when the approval polls need a bump.