I'd put in my 2cents too. Like most British-styled areas (colonies, ex-colonies, etc.) you always need to have a reason to be carrying a knife, and "self-defense" is not a reason. Fishing, camping, for cutting open envelopes or boxes are valid reasons, and most LEOs are happy to accept those reasons, even if you aren't currently engaged in, or about to engage in, cutting.
If you're a halfway decent chap (no overt offensive tattoos, bike-gang affiliation) and you're not found drunk on the streets or participating in a protest rally or walking around in threatening manner, most cops wouldn't even give you a second glance.
Of course, don't go walking around with a 9" bowie strapped to you (unless you can conceal it as well as Croc Dundee
) even if you fit the above description. It would be very difficult to justify opening boxes with a 9" bowies anyways, unless you can show that the box has teeth and a tough leathery skin and was about to eat you (because it is now illegal to kill the crocs without a license except in cases of threat of bodily harm.)
So get him a SAK (locking type) or a small folder 3" and under, that looks like a proper gent's knife. eg Spydie Viele,
William Henry,
Buck-Koji Hara.
But even something as classy as the
AGRussell Arkansas Toothpick (though it is a little over 4") would be fine. These links are just to give you an idea of what I'm talking about.
Tactical looking knives are ok too, but you are giving a gift aren't you?