Looking at vintage Off-Road boots catalog i just found those amazing boots specially made for Roger DeCoster around 1973/75.
I add them to a couple of pictures of him riding.
I know its not old enough for you Paul D'O but i'm sure you will appreciate ...
The world champion's motocross boot used by professiona racers.
Upper of soft and thick leather, front part and ankles padded; a dynamic but confortablestyle. Fastened by 7 patented buckles. Smooth sole and steel cap.
By working with some professional racers, always looking for innovations, the latest one has been created: a strong but light steel plate fixed to the front part of the boots guarantees safety even under the worst ground conditions. The padding under the plate protects from schocks.