20.3.—(1) If it appears to the court just and expedient to do so, it may order that any faculty, judgment, order or decree—
(a)be set aside (either in whole or in part); or
(b)be amended.
(2) If the court is considering exercising the power conferred by paragraph (1)(b) in a manner that would constitute a substantial change in the works or proposals already authorised by faculty the court must give such directions as to the giving of notice to the public and to such other persons and bodies as it considers just.