The compression swirl chamber design was called a "Comet" design (patented in 1931) and was subsequently licensed to a large number of companies for use in trucks, buses, tractors and cranes, as well as private cars and taxis. A Comet combustion chamber was used in the first Associated Equipment Company (AEC) diesel buses operated in 1931 by London General Omnibus Co, later part of the London Passenger Transport Board/London Transport. A later development of it featured in the world's first volume production diesel passenger car, the 1934 Citroën Rosalie.