as used on the N, N1 and U1 classes enabled the standardisation of Southern locomotives to continue. The locomotives were provided with heavy braking equipment in order to handle the trains of freight wagons with or without continuous brakes that were in use at the time. With this in mind the class was (unusually) provided with extra braking on the bogie wheels. Construction history An initial order was placed with Eastleigh railway works for ten locomotives, with the frames to be constructed at Ashford railway works and the boilers at Brighton railway works. However, by the time that Ashford had delivered the first five sets of frames in early 1930 a severe trade recession meant that they were no longer needed. The frames were stored and the boilers used as spares for the N and U class locomotives. By mid 1931 trade had recovered to allow construction of the initial five to be completed. These were delivered during January and February 1932. The components for the remaining five locomotives still on order were gathered at Eastleigh during 1932, but once again their construction was delayed pending a more sustained economic recovery, and the boilers were used elsewhere. A second batch consisting of these five locomotives together with a further five ordered in March 1930 were eventually delivered between April 1935 and April 1936. Eastleigh works was then committed to the construction of the Schools class and so the order was transferred to Ashford. Variations The two batches differed from each other because the Eastleigh batch had gravity sanding capability and steam regulators on the right hand side, whilst the Ashford batch had steam sanding and regulators on the left, as was common on most other classes of Southern locomotives. Modifications The first batch was modified between 1959 and 1960 to incorporate steam sanding, as this was already present on the Ashford batch. The right hand driving, however, remained. Livery and numbering Southern The first batch was turned out in black livery with green lining, and were numbered 1911–1915 with 'Southern' in yellow on the water tanks. The Ashford batch was outshopped in unlined black livery, and the initial batch were also converted to this new livery. These locomotives were numbered 1916–1925. Post-1948 (nationalisation) The locomotives retained their freight black liveries, and the BR crest was placed on the water tank sides. Numbering was per the BR standard numbering system, in