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.
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.