Permitted development  Development not permitted  Conditions  ( a ) See section 336(1) of the Town and Country Planning Act 1990 for the definition of “local authority”.  2 A.1.  Development is not permitted by Class A if—  A.2.  Development is permitted by Class A subject to the following conditions—  (i) any building, works, plant, machinery, structure and erection permitted by  Class A is removed; and  (c) on or before the expiry of a period of 12 months beginning with the date on which  the use of the land ceases for the purpose of Class A—  (b) any use of the land for the purposes of Class A ceases on or before 31st December  2020; and  (a) if the developer is not the local planning authority, the developer must, as soon as  practicable after commencing development, notify the local planning authority of  the development;  (f)  any moveable structure, works, plant or machinery required temporarily and in  connection with and for the duration of the development would be located in a  position—  (i) within 10 metres of any boundary of the curtilage of a dwellinghouse, or  (ii) within 5 metres of any boundary of the land.  (ii) the height of the highest part of the roof of the original building, or a height of  18 metres above the ground, whichever is the greater; or  (i) the height of the highest part of the roof of the original building, or a height of  6 metres above the ground, whichever is the greater, where any part of the  enlarged, improved or altered building is within 10 metres of any boundary of  the curtilage of the original building; or  (e) the height of any building enlarged, improved or altered exceeds—  (ii) the height of the highest part of the roof of the original building, or a height of  18 metres above the ground, whichever is the greater;  (i) a height of 6 metres above ground where any part of the new building is  within 10 metres of any boundary of the land; or  (d) the height of any new building exceeds—  (c) any part of the development would be carried out within 5 metres of any boundary  of the curtilage of a dwellinghouse;  (b) the land or building is, or contains, a scheduled monument;  (ii) a military explosive storage area;  (iii) a site of special scientific interest;  (a) any part of the development is on land which is, or forms part of—  (a) preventing an emergency;  (b) reducing, controlling or mitigating the effects of an emergency; or  (c) taking other action in connection with an emergency.  A. Development by or on behalf of a local authority( a ) or health service body on land  owned, leased, occupied or maintained by it for the purposes of— 