22.—(1) Anything done by a person in the course of his employment shall be treated for the purposes of these Regulations as done by his employer as well as by him, whether or not it was done with the employer’s knowledge or approval.
(2) Anything done by a person as agent for another person with the authority (whether express or implied, and whether precedent or subsequent) of that other person shall be treated for the purposes of these Regulations as done by that other person as well as by him.
(3) In proceedings brought under these Regulations against any person in respect of an act alleged to have been done by an employee of his it shall be a defence for that person to prove that he took such steps as were reasonably practicable to prevent the employee from doing that act, or from doing in the course of his employment acts of that description.