VH-JRB approached the airport from the south and on right downwind for runway 17R was told he was number one in the sequence. VH-IRH came in via Point Ormond to the north, also for runway 17R, the pilot being told to report at Southland. When he called at Southland the pilot of VH-IRH recived an acknowledgement but no instructions or traffic information. The two aircraft came into close proximity at about the base leg position. Both pilots saw each other in just enough time to deviate and miss. In nominating Southland as a reporting point for VH-IRH the controller selected a point close to the base position. He was initially unable to see VH-IRH when he called at Southland. As this was close to base leg position a conflict occurred before any further action was taken by him. Timely traffic information was not passed to both aircraft.