18   Development on residential zones

The Council shall not grant consent to the use of a building within Zone No 2 (a), 2 (c) or 2 (d) which was used as a dwelling house, boarding house, private hotel, backpackers hostel or residential flat building at the appointed day, for any non-residential purpose which would prevent its residential use, unless it satisfied that the local amenity is such that the building is no longer suitable for residential purposes.