> If someone wants a 14" blade, one can fetch some steel from a junkyard and apply an angle grinder to it.

I'm sure that's what the average 13-year-old wannabe gangster is absolutely going to do, spend 50 quid on a budget angle grinder and traipse around scrapyards for a lorry spring.

Yeah, that makes total sense.

Is there any *legitimate* reason why a child needs to be able to buy chef's knives?

Maybe wind the misplaced sarcasm down several notches please, it's unseemly particularly as knife making is easily one of the more popular goto shop projects in high school (outside the STEM nerd and theatre kids circle, I know) and that "wannabe gangsters" even in their teens have easy access to stolen goods at a discount or often five finger their own.

UK (and Canadian, Australian, etc) weapon disposal schemes frequently land home made weapons eg: https://kk.org/streetuse/english-ownerbuilt-weapons/ from 2006 is barely a trickle of the flood that gets swept up by amnesty programs.

Why isn't a child allowed to practice cheffing on their own? Say kid in a halfway or foster facility where the place doesn't have the knives and no one will buy them for them.

What are you going to tell them? That they're allowed a boning knife that'll easily cut every artery in a human but not a chopper because ooooh those are super duper scary? That they're not allowed any "chef's knife" but the steak knives for dinner are fine?

You know the average 13-year-old wannabe gangster can shave a shank on the sidewalk just as well, right? That a perfectly-capable-of-murder-and-menace device can be manufactured from just about anything? That a common 2x4 or bat or shoestring will do? And that preventing their committing crime with a larger knife is easier to police than a smaller concealable, right?