I can't find a photo of him but is that Nigel Orlebar in his GN/AC special Rabelro?
I was expecting you to know. Yes it is that car, and the point is yours. The car has already been a puzzle, but when I did a search it didn't appear for some reason. It does now! As you say, an old GN chassis with an AC 6-cylinder engine.
My next clue was going to be the Monty Python "Norwegian Blue parrot" sketch because it contains the words " the palindrome of Bolton is Notlob". The car's name Rabelro being the reverse of Orlebar - by all accoiunts he was the leader of Britain's Schneider Trophy air race team, hence the name of the Orlebar Schneider Ford 10hp based car which has been a previous puzzle.