https://emberleaf.com/Technical-Infomation/Uk-knife-lawUk knife law
Basic laws on knives
It is illegal to:
Lock knives (knives with blades that can be locked when unfolded) are not folding knives, and are illegal to carry in public.
- sell a knife of any kind (including cutlery and kitchen knives) to anyone under 18
- carry a knife in public without good reason – unless it’s a knife with a folding blade 3 inches long (7.62 cm) or less, eg a Swiss Army knife
- carry, buy or sell any type of banned knife (the list of banned knives is below)
- use any knife in a threatening way (even a legal knife, such as a Swiss Army knife)
The maximum penalty for an adult carrying a knife is 4 years in prison and a fine of ?5,000.