(1)Every planning authority shall consider, as soon as practicable after 1st October 1987, the question for which part or parts of their district a simplified planning zone scheme is desirable, and then shall keep that question under review.
(2)If as a result of their original consideration or of any such review a planning authority decide that it is desirable to prepare a scheme for any part of their district they shall do so; and a planning authority may at any time decide—
(a)to make a simplified planning zone scheme,
(b)to alter a scheme adopted by them, or
(c)with the consent of the Secretary of State, to alter a scheme approved by him.
(3)Schedule 5 has effect with respect to the making and alteration of simplified planning zone schemes and other related matters.