Thanks for those extra photos 72Must, very interesting.
I've found the source of the puzzle photo - it was taken in November/December 1955 at Estoril, Portugal.
The event was the Concours d'Elegancia de Estoril.
Class winners were an AC Ace, AC Aceca, Mercedes-Benz 300SL, Alfa Romeo Giulietta and a Goliath Coupe.
It doesn't mention where the Plymouth finished.