I think the poster meant that Britain does not have a first amendment protecting speech. And if you guys have a constitution, why is Christopher Hitchens always banging on that you don’t?
I think the key word here is ‘codified’. We absolutely do have a constitution. You can’t have universities offering ‘constitutional studies’, by constitutional experts, within a country who’s political system is defined as a ‘constitutional monarchy’ without actually having a constitution.
However, our constitution is not codified into a single document in the way, admirably, of the US constitution. But this does not mean that it does not exist.