“2. In these Regulations—
“3. (1) A proposal for the external design and siting of a building on a parcel of land, being a prescribed building within the meaning of section 6AA of the Building Act 1972 , is exempt from the application, by virtue of section 6 of the Act, of all of the provisions of Part VI of the Land Act—
(a) if the proposal relates to a letterbox—wherever it is proposed to be built on the parcel of land; or
(b) in any other case—unless the building is proposed to be built—
(i) between a front boundary and a building line;
(ii) less than 1.8 metres from a side boundary; or
(iii) less than 4 metres from a rear boundary;
of the parcel of land.
“(2) In this regulation—