<Li> All folding knives that are locking and have a one - handed opening mechanism (whether automatic, assisted - opening, or manual in nature). A knife that has only one of these two features may be legal to carry (namely provided it does not violate the principles below and above). </Li> <Li> All knives with fixed blades over 12.0 cm </Li> <P> Restricted - use knives may be carried if transported in a locked, sealed container, or if there is a commonly accepted legitimate purpose for carrying it, such as participation in a historical reenactment, sporting use (i.e. hunting), or as a necessary tool in a trade or business . The desire to defend oneself, or to use the knife as a tool without proof of necessity for its use is ordinarily not considered a legitimate purpose under the law . </P> <P> It is illegal to carry a knife for use as a weapon in attack or defense . The only general restriction is intended use, not the properties of the knife itself (in particular, there is no restriction of blade length, despite popular belief). However, in practice there will be significant leeway for interpretation for police officers and judges--and much will depend on whether an intended use other than as a weapon can be argued--for which the properties of the knife in question will be very relevant (bad: flick - knife, automated, long blade, neck - knife, tactical). So, carrying a knife that has its main use as a weapon will be illegal . In addition, it is not allowed to carry knives in certain places, such as courtrooms, to football matches, etc . Carrying knives is generally very unusual in towns, but not in the countryside . </P>

When did it become illegal to carry a knife in the uk