B.1 Development is not permitted by Class B if—
(a)the building as extended or altered is to be used for purposes other than those of—
(i)the Crown; or
(ii)the provision of employee facilities;
(b)the height of the building as extended or altered would exceed the height of the original building;
(c)the cubic content of the original building would be exceeded by more than—
(i)10%, in respect of development on any article 2(3) land; or
(ii)25%, in any other case;
(d)the floor space of the original building would be exceeded by more than—
(i)500 square metres in respect of development on any article 2(3) land; or
(ii)1,000 square metres in any other case;
(e)the external appearance of the original building would be materially affected;
(f)any part of the building as extended or altered would be within 5 metres of any boundary of the curtilage of the original building; or
(g)the development would lead to a reduction in the space available for the parking or turning of vehicles.