Armstrong Siddeley Development Co
1927 Armstrong Whitworth Development Co (chairman John Davenport Siddeley) was sold by Armstrong Whitworth to Siddelely; the name was changed to Armstrong Siddeley Development Co Ltd. Armstrong Whitworth would not use the company for any future development work. Included in the sale of the Development Company were its subsidiaries Armstrong Siddeley Motors and Sir W. G. Armstrong Whitworth Aircraft Ltd., as well as the aircraft engines business, and the shares in Crompton and Co. J. D. Siddeley was chairman of the new company[1]. Armstrong Whitworth disposed of their ordinary shares in the company and would not use it for any future development work, although later in the year the chairman of Armstrong Whitworth indicated they still had substantial interest in Armstrong Siddeley Development Co Ltd[2].
1927 Sale of most of the holding in Crompton and Co[3].
1928 Purchased the shares in A. V. Roe and Co that were held by Crossley Motors as a controlling interest[4].
1929 Continued profitability but capital needed for development so no dividend paid. Subsidiary companies included A. V. Roe and Co[5].
1935 Hawker Aircraft Ltd purchased Armstrong Siddeley Development Co and then sold the shares and 50% of the shares in Hawker Aircraft to a new company, Hawker Siddeley Aircraft Co Ltd, which had been formed as a public company for the purpose of combining the 2 largest UK aircraft manufacturers[6]. The companies acquired included the automotive and engine builder Armstrong Siddeley, the aircraft manufacturer Sir W. G. Armstrong Whitworth Aircraft, A. V. Roe and Co (Avro) and Air Training Services. The constituent companies continued to produce their own aircraft designs under their own name as well as sharing manufacturing throughout the group. The aviation pioneer Sir Thomas Sopwith became chairman of the new company and of Armstrong Siddeley Motors.
1958 the British government decided that, with the decreasing number of aircraft contracts being offered, it was better to merge the existing companies, of which there were about 15 surviving at this point, into several much larger firms. Out of this decision, came the "order" that all future contracts being offered had to include agreements to merge companies. Hawker Siddeley merged all of its aviation interests into one division, Hawker Siddeley Aviation; these companies were Hawker, Avro, Gloster, Armstrong Whitworth and Armstrong Siddeley[7].
1959 The aero engine business, Armstrong Siddeley, was merged with that of the Bristol Aero-Engines to form Bristol Siddeley Engines.