Actually, freedom of speech is guaranteed in the Bill of Rights, 1689. However, keeping a freedom requires the populace to care about it. In Britain's case everyone's too busy hating Europeans (then going on holiday there), being paranoid about jails full of paedophiles and being scared of terrorists and KnifeCrime(tm) to worry about the finer points of freedom of speech. Obviously these two are a pair of scum bags, so no-one cares to defend them, for what it's worth I believe their freedom of speech should be guaranteed, but try telling that to the populace.
Here are a few ideas of w h o, and wh at, might be responsible for this situation.
The 1285 Statute of Westminster even gave the English people the right (actually it was a requirement) to bear arms, it was due to this -- and technologically 'advanced' longbows -- that we managed to trounce those ghaslty frogs at Agincourt, but that's another story.
When speculation has done its worst, two plus two still equals four. -- S. Johnson