OK I have just seen lots of people here saying that locking knives are illegal to carry under UK law, even if the blade is under 3". My own research indicates that this isn't true - as you see above the Act refers to a 'folding pocketknive'. Nowhere does the act refer to a knife with a locking blade. The only way it could be illegal is if there had been a test case where the judge decided that a knife with a locking blade was not a folding pocket knife. As far as I can tell such a test case has never happened, so while it may be a grey area, it also appears that no-one has ever been prosecuted for possessing one either.139 Offence of having article with blade or point in public place
(1) Subject to subsections (4) and (5) below, any person who has an article to which this section applies with him in a public place shall be guilty of an offence.
(2) Subject to subsection (3) below, this section applies to any article which has a blade or is sharply pointed except a folding pocketknife.
(3) This section applies to a folding pocketknife if the cutting edge of its blade exceeds 3 inches.
(4) It shall be a defence for a person charged with an offence under this section to prove that he had good reason or lawful authority for having the article with him in a public place.
(5) Without prejudice to the generality of subsection (4) above, it shall be a defence for a person charged with an offence under this section to prove that he had the article with him—
(a) for use at work;
(b) for religious reasons; or
(c) as part of any national costume.
Interested if anyone has any more in-depth knowledge on this?