The Town and Country Planning (General Permitted Development) (England) Order 2015 No. 596

SCHEDULE 2 Permitted development rights

PART 19 Development by the Crown or for national security purposes

Class P – development by the Crown on operational Crown land etc relating to aids to shipping

Development not permitted

P.1  Development is not permitted by Class P if it consists of or includes the erection of offices, or the reconstruction or alteration of offices where their design or external appearance would be materially affected.