These locomotives were an improved version of the Class S56 tanks, and the final development of James Holden's Class T18 tank locomotives, sharing the same 16.5-by-22-inch (419 mm × 559 mm) cylinders, 4-foot-0-inch (1.219 m) driving wheels, and 13-foot-10-inch (4.22 m) wheelbase. There were three orders, each of ten locomotives, all built at Stratford Works between 1912 and 1923. The first batch were built as suburban passenger tanks and were fitted with Westinghouse air brakes. The second and third batches were built as shunting tanks and were fitted with steam locomotive brakes and vacuum train brakes.
Aldrich, C. Langley (1969). The Locomotives of the Great Eastern Railway 1862–1962 (7th ed.). Wickford, Essex: C. Langley Aldrich. OCLC30278831.
Baxter, Bertram (2012). Baxter, David; Mitchell, Peter, eds. British Locomotive Catalogue 1825–1923, Volume 6: Great Eastern Railway, North British Railway, Great North of Scotland Railway, Midland & Great Northern Joint Railway, remaining companies in the LNER group. Southampton: Kestrel Railway Books. pp. 103–104. ISBN978-1-905505-26-5.
Tourret, R. (1995). Allied Military Locomotives of the Second World War. Abingdon, Oxon: Tourret Publishing. ISBN0-905878-06-X.