The Q Class is a type of 0-6-0 steam locomotive designed by Richard Maunsell of the Southern Railway and constructed immediately prior to the Second World War for use on medium-distance freight trains throughout the network.

There was a continuing need for steam freight locomotives however, although the Traffic Department preferred mixed-traffic designs which could also haul passenger trains on the remaining non-electrified lines at peak periods.

[2][3] During his last year as the Chief Mechanical Engineer (CME) of the Southern Railway, Richard Maunsell decided on an inside-cylinder 0-6-0 tender locomotive to undertake this role, in what was to become the Q Class of 1938.

[citation needed] Maunsell's successor, Oliver Bulleid, oversaw the building of twenty members of the class at Eastleigh Works between January 1938 and September 1939.

[7] During the 1950s further experiments were carried out with the fitting of a British Railways Standard Class 4 plain blast pipe and small stovepipe chimney to no.

[8][9] The locomotives were adequate and reliable on secondary services throughout their working lives, their utility compounded by their light weight and steady handling.

The class was not considered sufficiently important for official preservation, and had it not been for Woodham Brothers's scrapyard in Barry, South Wales, no examples would have survived.

[citation needed] Due to its primary role as a freight locomotive, the Q Class carried the Southern Black livery.

Even though they were built under the tenure of Bulleid, the locomotives never followed his adaptation of the UIC classification system which refers to the number of leading, trailing and driving axles – in this case three.