Between May 1901 and July 1902, Walkers Limited delivered 20 locomotives to the Queensland Railways. Per Queensland Railway's classification system they were designated the 6D16 class, the 6 representing the number of driving wheels, the D that it was a tank locomotive and the 16 the cylinder diameter in inches. The 6 prefix was later dropped, when the remaining non six-wheel tanks were withdrawn.[1][2]
They were built to the 4-6-2T wheel arrangement. However the combination of double front bogie and single rear truck caused derailments and in 1904/05 all were rebuilt with a four-wheel swinging bolster bogie at both the front and rear thus becoming 4-6-4Ts. Between 1912 and 1918, all were fitted with new round top boilers and larger bunkers.[1][2]
They were mainly used on suburban passenger services in Brisbane, principally between Ipswich and Sandgate although they did operate on occasions to Kingston and Lota.[1][2]
In July 1935, 375 was married to a tender from a B15 class and reclassified as a B16D class. It was followed by 376 in July 1939. Both were deployed on freight services within Brisbane. Twelve were written off in 1942/43 with the remaining eight following in 1950/51.[1][2]
