special Chipmunk's livery

Hello everybody, I’m a new member.
I lately came across the following video
https://www.youtube.com/watch?v=p4HzYLriIM8
It shows Prince Carles taking a flying lesson in a Chipmunk with a very unusual livery. Entirely red and without identification markings. Also, the attending technicians wear unusual white coats. Presume it’s a Chipmunk temporarily in charge to the Queen’s Flight in those days. Can anyone in the forum confirm? Thanks beforehand