Victor Golf............
You beat me to it by about three years. My first visit to Thruxton was to attend Thruxton Air Races 16 September 1962. Seem to recall there was a Jackaroo race with about six aircraft taking part. Down in the hangar I remember seeing Miles Falcon G-ADTD, this was to crash a week later practising for Shoreham Air Races.
Think your "bearded aviator" could be Pat Shea Simmonds who was the "test pilot" for the Jackaroo.