Knives in the UK are age restricted for purchase. Anyone can carry a folding pocket knife with a blade less than 3" without needing a reason. Any other mechanism, fixed blade, or longer blade require a lawful reason to carry. This includes recreation (e.g. fishing, camping) work (e.g. joinery, cooking).

There are a handful examples of overzealous officers misunderstanding and detaining for the wrong reasons, and plenty of examples of people who pretended to the media it was for innocent reasons until the court case showed otherwise.

For your point about forks, I'll note that they are actually covered by the same law; as are all pointed objects.