Source?

I agree that BBC is a propaganda machine. Arguably the first.

Either way, the fear mongering about stabbing murders is highly dubious.

Are these actually happening? They would be easy to stage, or just make up.
Most to the "mass shootings" in the us are state run police drills that are reported as incidents.

I can supply you with plenty of evidence if you're interested.

I suspect that the goal of all of this is to manufacture fear of "the other" in order to pass additional "Patriot Act" style laws and remove more freedom. If they've banned the sale of knives, then they're intentionally disarming the public.
You may want to go stock up on knives and hammers... JK!

But seriously. Are people truly frightened of stabbings from strangers? The British are far from cowardly. They love fighting and violence. It doesn't make sense.
It seems like a hoax.