(1)Subject to subsection (4) below, it shall be the duty of each of the following authorities—
(a)a district council,
(b)a London borough council,
(c)the Common Council of the City of London, and
(d)the Sub-Treasurer of the Inner Temple and the Under Treasurer of the Middle Temple,
to carry this Act into execution in their district.
(2)In this Act, except where it is otherwise expressly provided, " local authority " means an authority mentioned in subsection (1) above.
(3)A local authority having jurisdiction in any part of a port health district (including the London port health district) shall not discharge in relation to it any functions which are functions of the port health authority.
(4)Subsection (1) above shall have effect subject to the provisions of this Act with respect to—
(a)port health authorities,
(b)Regional, Area, District or special health authorities, and
(c)county councils,
and shall not impose on any authority specified in that subsection a duty to discharge, in relation to a united district constituted under section 6 of the [1936 c. 49.] Public Health Act 1936, any function which is a function of the joint board for that district.