hmmm now that is a drama,
i understand the wish to rock the boat and get them to understand that your lad was right and what your doing isnt illegal......however this could cause them to get their backs up, which in turn could cause them to find other ways to make it difficult for you. to this end i would recommend getting the information contained in the law printed off and retained for taking with you or your son whenever you go. you basically have to have everything set up to answer any question they may have, so proof of id, adress etc, permission, the laws, and anything else specific