I flew the Gnat as a student in 1967. A delightful aircraft to fly - until you got an emergency, either for real or (more likely) instructor induced. Then you had to get the emergency drills exactly right, or it became a real handful. It soon sorted out those who could cope from those that couldn't. The Hawk (which I also flew later on in the '80s) was much more forgiving and docile, so in order to assess the students' capabilities more thoroughly, they were put under greater pressure by increasing the workload in the cockpit on many of the later sorties of the course.