25.—(1) Subject to paragraph (2), the Executive may, by a certificate in writing, exempt any person or class of persons from all or any of the requirements or prohibitions imposed by regulations 4, 5, 11, 12, 20 and 21(5) to (7) of these Regulations and any such exemption may be granted subject to conditions and to a limit of time and may be revoked by a further certificate in writing at any time.
(2) The Executive shall not grant any such exemption unless having regard to the circumstances of the case and in particular to—
(a)the conditions, if any, which it proposes to attach to the exemption; and
(b)any other requirements imposed by or under any enactments which apply to the case,
it is satisfied that the health and safety of persons who are likely to be affected by the exemption will not be prejudiced in consequence of it.