Thanks Ginaro, I've corrected the postcode.

Mount Melville is the name of the country house which is now incorporated into Duke's Golf Course. The postcode is for the golf course as a whole. The house itself was derelict for many years so was presumably removed as a postal address. It's now being renovated. It's worth adding as an item in itself because (a) it's very large and (b) it has a rich history.