B.1 Development is not permitted by Class B if—
(a)the plant or machinery would—
(i)if the land or pier is within 3 kilometres of the perimeter of an aerodrome, exceed a height of 25 metres or the height of the highest existing structure (whichever is the lesser), or
(ii)in any other case, exceed a height of 25 metres;
(b)in the case of an extension to an existing building or structure, that building or structure would as a result exceed 5 metres above ground level or the height of the roof of the existing building or structure, whichever is the greater; or
(c)in any other case, the height of the building or structure erected, extended, altered or replaced would exceed 5 metres above ground level.