In the Summer of 1941 Supermarine Spitfire Mk II "P7674" was delivered to Hucknall and fitted with a Crecy mock-up to enable cowling drawings and system details to be designed. It was planned for the first production Spitfire Mk III to be delivered to Hucknall in early 1942 for fitting of an airworthy Crecy, but this never took place. A Royal Aircraft Establishment report (No. E.3932) of March 1942 estimated the performance of the Spitfire fitted with a Crecy engine and compared this to a Griffon 61-powered variant. The report stated that the Crecy's maximum power output would be too much for the Spitfire airframe but that a derated version would have considerable performance gains over the Griffon-powered fighter.