I don't know who he was but I know he didn't finish.
The results brochure has four 80+ riders registered, three started, but none finished.
The ACP Trophy for the oldest rider was presented to " Jean GUILLOT (86) 4 September 1941"
(ETA - The (86) had me confused and thinking he was one of the three starters, but I now see Jean Guillot was only 77. He finished in 87:59. It was his seventh finish, his first in 1971 was completed in 68:17. So maybe he will be back in 2023.
(86) seems to be an area or club code.)