Luton/Channel Islands.
I was an ATCA at Luton 1964/65. At that time Derby Airways operated to both Jersey and Guernsey with C47s in the summer with the occasional Argonaut to JER. Sometimes, the Herald, G-ASKK, turned up too. Some days in the summer those services originated at Cambridge.
They also operated a service to Belfast via Derby also with the Daks (they had about 7).
When the development of Castle Donington was announced Derby Airways then announced their name change to British Midland.
The terminal at that time was a collection of wooden huts and both of the resident operators, Autair and Euravia (who also used the Skyways of London name) had their offices in huts.