Honestly, I don't have a particular problem with the
general requirement to have a 'good reason' to be carrying a lockable folding/fixed blade knife of any length or a penknife of greater than 3".
The length specs are a bit arbitrary and if I were the one setting them, I'd have gone with a more usable 4" rather than the 3" it is. Also, of course, there are designs that provide the (to me) biggest practical advantage of a locked blade, notably one handed opening (annoys me, recognising the need for a knife but having only one hand free, and not being able to open the knife), that makes a mockery of the implementation of a law designed to prevent people pulling a knife and having it ready to stick in someone else in a fast single movement.
But eh...the law is almost always a blunt instrument and implementations are often written by civil servants in a hurry, without subject matter expertiese. They are also often given a brief by their political masters which is less about the best way of solving the problem, but rather more a way that is most likely to
look like it solves the problem to people of limited logical and analytic faculties (AKA most of the voting population
).
As for the police, I've always taken a pragmatic approach of 'catching more flies with honey than vinegar'.
On the two occasions I've had to explain my possession of a potentially 'offensive weapon' in a public place (one on the way back from a bit of rabbit control on a mate's smallholding, where I had a 4" scandi style sheath knife and one where I had a 3-1/2" locking knife that I'd forgotten was in my backpack), the first was easy to explain and the second just required a quick explanation of the mistake that lead to the knife being where it was, an embarassed apology, and a promise to head straight home after I'd been where I was going.
If the copper is a basically sensible, decent one, then they appreciate the courtesy and will react accordingly, and if not, the gentle 'ass-kissing' often can attenuate the fact that the copper is a bell-end.
That said, I'm not a person of colour, or particularly 'known' to the police (and if you're doing nothing illegal at that point, being
generally a 'person of interest' to the police
ought to be irrelevant) I'd be interacting with, so results may vary.
If one isn't a die-hard libertarian, and thus of the option that things like this are the thin end of the wedge (a perspective, I should add, I have some sympathy for if not actual agreeement), the knife laws in the UK can be a minor inconvenience, in some respects a bit silly, and of course, not particularly effective in preventing knife crime (then again, very little law is particularly good at
preventing criminal acts by habitual criminals), but rarely a significant problem.