D. The erection or construction of a porch outside any external door of a dwellinghouse.
D.1 Development is not permitted by Class D if—
(a)permission to use the dwellinghouse as a dwellinghouse has been granted only by virtue of Class M, N, P or Q of Part 3 of this Schedule (changes of use);
(b)the ground area (measured externally) of the structure would exceed 3 square metres;
(c)any part of the structure would be more than 3 metres above ground level; or
(d)any part of the structure would be within 2 metres of any boundary of the curtilage of the dwellinghouse with a highway.