Gustav Maclure was asked to design an 11.9hp sidevalve engine by a customer who promised orders. That contract did not materialise, but Maclure had already used his experience at Rolls-Royce to design a high quality engine. On completion John Weller of AC Cars approached Anzani to purchase an engine until their own 6-cylinder engine was available and placed an order in 1919 for the 1,496cc sv engine. This order was terminated in 1925 when SF Edge of AC Cars, and now at Director at Anzani, decided to manufacture their own version of the Anzani engine, at which point Anzani went bankrupt. Anzani had supplied engines to a number of other manufacturers, but their sales declined against mass production makes and suddenly the Anzani market had gone. However, designer Maclure had left Anzani in 1923 to set up his own engine business, essentially manufacturing the same engine that he had designed for Anzani, but now as a 1,500cc ohv unit sold under the Plus Power name. Plus Power sold engines to Frazer-Nash but went bankrupt in a year, and the Anzani engines were taken up by Frazer-Nash. AC Cars were manufacturing their own version of the Anzani engine at the Cubitt Car Company, and they called in Maclure to cure the faults in the Cubitt design which had been plagiarised from his own design; as a bankrupt he must have been pleased to accept. The Cubitt engine only lasted 2 years as AC Cars stopped selling 4-cylinder cars in 1927. Archie Frazer-Nash then put in a rescue for Anzani as British Anzani in 1927, and a new sohc engine was designed, along with vee-twins and marine engines. When Aldington bought out Frazer-Nash the British Anzani wing did not fit the business needs. However T.D Ross joined Anzani from Austin and under him the R1 supoercharged dohc engine was designed. From 1934 Aldington was back into British Anzani after Ross had resigned, and by 1936 AFN had bought out British Anzani. However, Aldington became distracted by a growing and profitable relationship with BMW and almost ignored British Anzani. Charles Henry Harrison joined as designer and Anzani moved into motorcycle and power boat engines, some of which ended up in Microcars.