The Newbury Diesel Company was a manufacturer of large marine diesels from its early days and was originally an offshoot of another well known Newbury company, Plenty’s. Amongst other things, Plenty’s built steam engines until, with the development of a combined steam and oil engine, they decided that they would set up a separate company under the leadership of a brilliant engineer, Mr H Kent Norris. A detailed history by Peter Humphreys can be viewed in pdf format.
The factory in Kings Road Newbury, originally the Plenty boiler shop and then the location of the Plenty-Still company, became the Newbury Diesel Company in 1932 when it separated.from Plenty & Co. It produced, during its life, a range of marine diesels designed by Kent Norris. These were given the trade name of Sirron Diesels, Norris in reverse and which became the standard engines of the Everard Shipping Company that took a controlling interest in the Newbury Diesel Co.in 1936.The relationship between Everard's, the Plenty Company and the Newbury Diesel Company was forged at the turn of the century by one of the sons of the founder, Frederick T Everard. The three sons were Will Everard and Fred Everard who were shipwrights and Alf Everard who trained as an engineer at Plenty & Son Ltd at Newbury. It was this link that would have set the seal for the use of Plenty engines and subsequently Sirron diesels by the Everard company.
In 1967, the factory produced its last Sirron engine but continued to manufacture marine control apparatus under the leadership of Peter Humphreys and Terry Barnard but renamed Newbury Diesel Controls Ltd.. The Kings Road factory closed in 1981 and the remaining workforce transferred to a new location.
Most of the manufacturing companies in Newbury were struggling at that time but Plenty’s managed to weather the storm as did Newbury Diesel Controls Ltd. The latter was sold eventually to Radamec and are still in business. Plenty's, like the Diesel company also changed direction and sold off their sites in Kings Road and Cheap street to concentrate on the manufacture of pumps and specialist valves.
Apart from the benefit to Newbury of a factory employing highly skilled engineers, the company turned out a number of apprentices into both its own and other work forces. A further benefit Newbury derived was the installation in 1922 of a P50 Newbury manufactured diesel generating set that was used by the local electricity generating company. It was located in a unit at Greenham Mill close to the Kennet, eventually becoming a standby generator until the early 1950s when the national grid took effect.