Class 77—(1) Development carried out by or on behalf of the Crown on operational Crown land for operational purposes consisting of–
(a)the installation of additional or replacement plant or machinery;
(b)the provision, rearrangement or replacement of a sewer, main, pipe, cable or other apparatus; or
(c)the provision, rearrangement or replacement of a private way, private railway, siding or conveyor.
(2) Development described in Class 77(1)(a) is not permitted if–
(a)it would materially affect the external appearance of the premises; or
(b)any plant or machinery would exceed a height of 15 metres above ground level or the height of anything replaced, whichever is the greater.
(3) In this class, “Crown land” does not include land in or adjacent to and occupied together with a mine.