Legal to Carry in UK Handy Niknaks UK Legal Knives A large number of normally law-abiding citizens are unwittingly breaking the law on a daily basis by having a lock-knife in a public place. The length of the blade is irrelevent, as lock knives are treated the same as fixed blade knives in the eyes of the law in the UK.

The only knife allowed to be carried in public in the UK is a non-locking pen knife with a blade no longer than 3 inches. There are certain exceptions, for example where the knife is needed as a tool of the trade or part of a traditional costume. This is the legal definition of 'Penknife' and it is perfectly legal to carry a penknife without any particular reason.