Grace's Guide is the leading source of historical information on industry and manufacturing in Britain. This web publication contains 134,742 pages of information and 213,800 images on early companies, their products and the people who designed and built them.
1905 Wolseley Tool and Motor Car Co purchased the Siddeley Autocar Co, with founder John Davenport Siddeley in charge. Siddeley took control of the merged concern, renaming the marque Wolseley-Siddeley. The company made the stately Wolseley-Siddeley motorcars. They were used by Queen Alexandra and the Duke of York, the later King Edward VII.
1905 Produced 6 h.p., 12 h.p., 15 h.p., 18 h.p., 25 h.p., 32 h.p. and 70 h.p. models of car. These were constructed by Wolseley. 
1905 For the 1905 Gordon-Bennett Eliminating Trials they produced a 100-hp car using four-cylinders and of 15,685cc capacity. Built in Birmingham and registered as BH 444. Martin Harper was one of the mechanics. Sidney Girling was the official driver with Cyril Bianchi as his mechanic. The car crashed out of the trial race.
1905 Herbert Austin leaves and Siddeley became General manager.
1905 July. Private trial in Europe against De Dietrich over 4,400kms to test reliability. Both completed the trail and it was declared a dead-heat.
1906 The range included horizontal-engined models from the original Wolseley designs and vertical-engined models from Siddeley.
1908 August. Details of their cars including 14-hp and 45-hp.
1909 John Davenport Siddeley resigned from Wolseley and took over the Deasy Motor Car Manufacturing Co, which company became known as Siddeley-Deasy. He took with him J. A. Simmons, A. G. Asbury and Percy Smith.
1909 October. Details of the Wolseley-Siddeley 12-16hp car.
1909 November. Details of the Wolseley-Siddeley 40-50hp car.
1910 6 Wolseley-Siddeley models were listed in the Red Book.
1910 Wolseley production was concentrated at Birmingham.