I remember this event very clearly and have been in touch with relatives of Col Sweet through a posting on Pprune a number of years ago. The accident report from memory concluded that the wings had not extended fully and the aircraft stalled. The site was cleaned up very quickly. The map references given were correct at the time but the coordinates have changed with updated OS Maps. The site is to the right of the hill going up Tullybaccart from Coupar Angus to Birkhill.