Peter Hain and free-speech

Peter Hain, that bastion of probity, has threatened the BBC over its decision to invite Nick Griffin onto Question Time on Thursday. He is reported to have said that

"If you do not review the decision you may run the very serious risk of legal challenge in addition to the moral objections that I make.

"In my view, your approach is unreasonable, irrational and unlawful."

Why is free speech so anathema to so many on the left of British politics?