"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."
"Without prejudice to the generality of subsection (4) above, it shall be a defence for a person charged with the 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."
"... forgetfulness may be an explanation, it cannot be a good reason."
"When you are found in a public place with a prohibited knife on your person, it is no defence to just say 'I forgot I had it'."