Maunsell designed these 'Woolwich' mixed traffic locomotives for the South Eastern & Chatham Railway and the first took to the rails in 1917. It was Maunsell's first locomotive design for the SE&CR and was intended for heavy freight work. Despite a number of teething problems, it proved to be a very successful design. To generate work for unemployed munitions workers at the end of the First World War, 100 of the locomotives were to be built at Woolwich Arsenal, thus the 'Woolwich' nickname. However, the quality of workmanship was poor and the order was not completed. Some were sold as kits of parts, while Ashford finished the job by rebuilding others. Eventually, the Southern Railway had a class of 80. This hotchpotch construction resulted in a lot of detail differences which a model maker has to be aware of. Smoke deflectors were a late addition to many of them.

They worked throughout the Southern network and during the Second World War they played an important roll in transporting freight to the South Coast ports. All 80 survived into BR ownership and the frames were modified in the mid '50s. Class 33 diesels began to take over their work and the first withdrawals occurred in 1962 - the last in 1966. 31874, of 1925 vintage, was preserved and at one time took on the roll of 'James the Red Engine' on the Mid-Hants line.

The Midland Great Western Railway in Ireland needed some new more powerful engines in the 1920s and so it bought 21 of the locomotive kits from Woolwich Arsenal and assembled 20 of them at the Broadstone and Inchicore Works as 5'3" gauge engines in the K1 Class. A further six were later bought and built with larger wheels as the K1a Class.