The BB18¼ was a light 4-6-2 “Pacific” for mixed traffic that was ordered by the Queensland Railways after World War II from Vulcan Foundry in England. While the B in the designation stood for three coupled axles and the 18¼ denoted the cylinder diameter in inches, the second B was added to distinguish it from the earlier class B18¼ Pacific. The first 35 were built by Vulcan Foundry in 1950 and 1951. 20 more followed from Walkers Limited between 1955 and 1958. No. 1089 was the last steam locomotive placed into mainline service by any Australian railway company.

They had similar tasks as their predecessors, what included goods, suburban and long distance passenger traffic. Although they had a fairly low axle load, some bridges in the QR network were reinforced in the fifties to further increase their route availability. While long distance passenger services dominated their tasks in the first years, these were later taken over by diesel locomotives. Six have been preserved and 1037 is still in working condition. It is being owned by DownsSteam in Toowoomba.