s 54D Effect of altering scheme
(1) Alterations to a scheme have effect from the day they are made. (2) Subsection (3) applies where— (a) development for which authorisation is granted by a scheme has begun, and (b) the scheme is subsequently altered. (3) The authorisation that the scheme grants for the development is unaffected by the alteration, unless the scheme (as altered) provides otherwise. (4) But the scheme may not provide that the alteration affects the authorisation for the development if the effect would be to remove authorisation for anything that was authorised by the scheme when the development began.