s 27B Notification of completion of development
(1) A person who completes development for which planning permission has been given must, as soon as practicable after doing so, give notice of completion to the planning authority. (2) If an application to a planning authority for planning permission discloses, in the opinion of the authority, that the development in question is to be carried out in phases then any such permission granted is to be granted subject to a condition, imposed under section 37(1)(a) in respect of each phase except the last (notice of the completion of which is to be given under subsection (1)), that as soon as practicable after the phase is completed the person carrying out the development is to give notice of that completion to the planning authority.