Patronage declined rapidly on government bus services from 1950 as people deserted public transport in favour of the private motor car. To ease the burden of declining revenue, government and private bus operators alike turned to driver only operation as an economy measure. In addition a replacement fleet was needed for the ageing half-cab single deckers which were coming to the end of their service lives. Wear and tear had been accelerated by their intensive use in the war years.

A design was developed by the Department of Government Transport which comprised modern ideas such as standee windows, air operated doors and full width body fronts, but with retained exposed radiators. A total of 172 buses known as "31 seaters" were built between 1951 and 1955 by the Commonwealth Engineering Co. Granville, Sydney. 50 were constructed on A.E.C. Regal III chassis, 50 on Leyland OPS2/1 Chassis, 20 on Daimler CVG6 chassis. The final group of 52 buses, 34 on Leyland OPD2/1 double deck and 18 on A.E.C Regent III double deck chassis.

Orders were placed for 20 Daimler double deck chassis in 1945. Due to the massive fleet replacement programmes taking place all over the UK after the 2nd Word War, deliveries did not occur until the early 1950's. In view of their late arrival it was decided instead to fit them with single deck bodies for driver only operation.

While a few examples were used at North Sydney depot for a number of years on the routes to and from the inner harbour wharves, 2669 is one bus that spent its entire working life based at Brookvale depot for use in the Manly Warringah area. New in 1952, it was withdrawn in 1973 and sold to Casula Wreckers where it was rescued by an enthusiast. The bus has since been acquired by the Association for display in the Museum.