Britsh Westpoint - Nearly made my list - twice (updated it with Balair and Swissair). Late 1960's operated passenger daks out of Gatwick as an Air France affiliate (Tiny Air France Logo, I think on the door?). Only once ever saw one of their Rapides (Thinks it was delivering a part for a Dak), made my 'spotty spotter day'.
Jersey Airlines were a Heron Operator. I was once the owner of two professionally taken photos of their Aircraft which were disposed of many years ago due to having coffee or similar spilt over them! Careless youth!
DIH