The law (Criminal Justice Act 1988, S.139) say this about the Statutory defence:
(4) 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.
(5) Without prejudice to the generality of subsection (4) above, it shall be a defence for a person charged with an 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.
So, yes, the wording does make the interpretation (at least under sub-section (4) somewhat subjective. However, as has been suggested, carry them in a suitable container (preferably locked). If you’re travelling by car keep them in the (locked) boot. Try to have some evidence of the event you are attending.
No plod should consider an arrest or prosecution if you take those measures. If they do you would have a perfect defence under sub-section (4).