A Rockhampton City Council airport vehicle had been cleared by the Aerodrome Controller (ADC) to enter all movement areas for a runway inspection. This clearance enabled the driver to enter any runway without obtaining further clearance. Subsequently, a Fokker F28 VH-EWA was cleared to land on runway 15. When the aircraft was on short final the pilot noticed a vehicle on the runway approximately 1400 metres from the runway threshold. The pilot commenced a go-round and the ADC instructed the vehicle to vacate the runway immediately. The vehicle then cleared the runway, and the F28 made a normal circuit and landing. The ADC stated that he had inserted the "runway occupied" strip into the active display board as is normal procedure when runway inspections are in progress. When the F28 turned base he scanned the runway, and as he did not sight the vehicle on the active runway he cleared the F28 to land. When the aircraft was on short final, another scan of the runway revealed that the vehicle had moved into view from behind two obstructions, a window mullion in the tower and a concrete light tower on the edge of the apron. The lighting tower is some distance from the tower cab and requires considerable physical displacement by the controller to effectively see behind it. Local procedures have been changed as a result of this occurrence. Vehicles on the movement area are now required to obtain a specific clearance before entering a runway. Relevant Factors 1 The vehicle was not required to obtain specific clearance to enter the runway and entered the runway without the controller noticing. 2. The vehicle stopped on the runway in a position which was obscured by obstructions. 3. The controller failed to adequately scan the full length of the active runway before clearing the F28 to land.