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Dudbridge Iron Works of Stroud in Gloucestershire.
1899 Humpidge, Holborow and Co. was reorganised; their steam-engine business was sold; the works were devoted to the manufacture of gas and oil engines; the title of the Company was altered to the Dudbridge Iron Works; James Dickerson Humpidge became co-managing director with Mr. H. Theo. Humpidge and Mr. T. G. Smith.
1900 Paris Exhibition. Description of oil and gas engines shown. The firm employs about 200 men and produces one engine per day. The largest engine is 96 hp.
1901 Portable oil engine at the Royal Agricultural Society's Cardiff Show.
1903 'A FLY-WHEEL BURSTS. FITTER KILLED AND DIRECTOR INJURED. At Dudbridge Ironworks, Stroud, Saturday, a new 120-h.p. gas engine was being tried when the fly-wheel suddenly burst, and the fragments flew into hundreds of pieces. A fitter named French was killed, and Mr. J. D. Humpidge, a director of the firm and President of the Gloucestershire Engineering Society, who was watching the operations, was seriously injured about the head. The roof of the works was wrecked, and a piece of iron weighing 3cwt. pierced the roof and descended into another room, narrowly missing the men there employed.' 
1904 Offering portable oil engines from 2 to 20 bhp
1911 Catalogue issued on their gas engines and gas producing plant
WWI Maker of aeroplanes; the firm was very active on war work, principally for the Air Force and the Admiralty.