In 1942, in anticipation of an invasion of the Continent, it was decided to design and construct a heavy shunting locomotive. R.A. Riddles, seconded from the LMS to the Ministry of Supply, took charge of the design. Initially the LMS Standard shunter, known to many as the Jinty, was chosen. However, under pressure from the locomotive building industry, it was sensibly decided that an industrial tank locomotive with shorter wheelbase was a simpler and more easily maintained alternative for the duties required. The Hunslet Company took the lead and the shunting engines known as the Austerity saddle tank, were born.
The design of the Austerity was summarized by Don Townsley, the knowledgeable historian of the Hunslet engine company, as an amalgam of the standard Hunslet 18 x 26 in. cylinder steelworks shunter, first built in 1937 for Guest, Keen and Baldwin's at Cardiff, and locomotives of similar power built to the order of Stewarts and Lloyds in 1941. Both designs were a natural progression from an 0-6-0 side tank, Works no. 1506, built in 1930 for the Pontop and Jarrow colliery railway. In essence the frame of the Jarrow machine was married to the Guest, Keen engine and the extended saddle tank of the Stewarts and Lloyds variant. A larger coal bunker was fitted and the cab roof had rounded eaves to provide a better loading gauge clearance. This 'trimming' of the cab was to some extent necessitated by the increase in wheel diameter from 4 ft. 0 ½ in. on the previous designs to 4 ft. 3 in. on the Austerity so as to provide greater clearance above rail level and to permit the use of easily replaceable under-hung springs. The boiler proportions were chosen to give quick steaming without being uneconomical during standby periods.
The first 'Austerity' left Hunslet's works in Leeds on 1 January 1943, less than six months after the initial order for fifty locomotives had been placed. Hunslet's production was supplemented by Robert Stephenson and Hawthorns, Hudswell Clarke, Bagnall and, later, Vulcan Foundry and Andrew Barclay. Of the 377 Ministry locomotives supplied between 1943 and 1946 Hunslet built 120, RSH ninety, Bagnall fifty-two, Hudswell Clarke fifty, the Vulcan Foundry fifty and Andrew Barclay fifteen. After the war, 106 further Austerity locomotives were built, seventy-seven for the National Coal Board, fifteen for the steel industry and fourteen more for the Army. With the exception of two from Robert Stephenson and Hawthorns Ltd and eight from the Yorkshire Engine Company, these all came from Hunslet. There were very few observable variations throughout the 485 locomotives as built.
After the war the LNER bought 75 from the Ministry of Supply for general shunting work, becoming class ‘J94' (power classification 4F). They became widely used in industry, while the War Department retained a number for use at military installations around the country. Others remained on the Continent with many sold to the Netherlands.
The K&ESR locomotives were all built by Hunslets for the Army after the war. Their works numbers are: No. 23, Wks No 3791 (built 1952); No. 24, Wks No 3800 (built 1953); No. 25, Wks No 3797 (built 1953).
Each was stored initially at the Longmoor Military Railway. The WD logbook for No. 23 shows it was put into service at Bicester in 1956 as WD 191 Black Knight, generally repaired in 1957/58, stored in May 1962 at No. 1 Engineers Supply Depot, Long Marston, before final transfer in December 1967 to No. 1 Railway Group, Royal Corps of Transport at Shoeburyness. There it worked for only nine months before again being put into store. From Shoeburyness it was sold out of Army use, arriving at Rolvenden in February 1972. It ran a total of 23,178 miles during its 20 year military career.
No. 23 entered service in August 1974, No. 24 becoming available three years later. In 1977 Dr. John Coiley, then Curator of the National Railway Museum, named the former Holman F. Stephens after the Railway's engineer and first Managing Director.In almost continuous use it returned once again from overhaul in 2004.
No. 24 saw service at Bicester as WD 200 before transfer back to Longmoor and then went to Shoeburyness. Upon disposal it was privately purchased for use on the K&ESR, arriving in January 1971. No. 24 initially carried the name William H. Austen in honour of Stephens' successor but this has been changed in recent years to the traditional K&ESR name Rolvenden once carried by Terrier No. 5.
No. 25 worked at various Army locations, including Longmoor in 1957, before coming to the K&ESR in 1977 from the Command Ordnance Depot at Bicester where, as ARMY 197 it had been named Sapper. During its first two years it remained Army property and remained on a back siding at Rolvenden. The Ministry of Defence disposed of it to a small group of members in October 1979. A ‘low mileage' model it re-entered service at the end of 1981 in a distinctive lined blue livery similar to that used at Longmoor and not without resemblance to the K&ESR livery used in Colonel Stephens' days. As the Sapper nameplates were not available the locomotive was renamed Northiam by TV personality Andrew Gardner in April 1982. The locomotive has remained in service ever since
