Got it at last. It's an Amero GT built in 1974 by Gordon Hook, the first of 6 such cars. It has a 3.3-litre Holden engine, and was originally made from parts of a Standard Vanguard Phase III ! Present owner Mark Stacey replaced the front end with Cortina Mk4 parts, and the rear end which was Holden based is now a Nissan Skyline.