Looks like a Fairmile B to me too, although much modified. The Royal Australian Navy batch of Fairmile Bs was numbered 801 to 827 and built by Green Point Boatyard and Halvosen in Sydney and by Norman Wright in Brisbane. The Royal New Zealand Navy block was 400 to 411, built by Associated Boat Builders, Bailey, Shipbuilders Ltd, Voss Ltd in Auckland and by three yards in Calcutta.