 A supercharged Napier Lion VIID was used, with over three times the power of the previous Blue Bird and a large premium over Golden Arrow's unsupercharged Lion VIIA.This was not the first use of supercharging for , but was the first combining supercharging with the large displacement aero engines that had previously been relied upon for their gross output.Golden Arrow's innovative vertical aerodynamic stabilising fin was also used, a first for Campbell.