s 4 Other defences.
(1) It is a defence for a person charged with an offence under section 1 to prove that he did not know or suspect, and had no reasonable grounds for suspecting, that the way in which the knife was marketed— (a) amounted to an indication or suggestion that the knife was suitable for combat; or (b) was likely to stimulate or encourage violent behaviour involving the use of the knife as a weapon. (2) It is a defence for a person charged with an offence under section 2 to prove that he did not know or suspect, and had no reasonable grounds for suspecting, that the material— (a) amounted to an indication or suggestion that the knife was suitable for combat; or (b) was likely to stimulate or encourage violent behaviour involving the use of the knife as a weapon. (3) It is a defence for a person charged with an offence under section 1 or 2 to prove that he took all reasonable precautions and exercised all due diligence to avoid committing the offence.