13. In section 156 , after paragraph (b), the following paragraph shall be inserted:—
“(c)a requirement or prohibition imposed by or under health and safety regulations which expressly apply to all mines or quarries, any class of mine or quarry or a particular mine or quarry being a requirement expressly imposed on that person or on persons of a class to which, at the time of the contravention, he belonged, or a prohibition expressly imposed on him or on persons of such class or on all persons from doing a specified act”.