Incorrect rank?
Surely the rank of the character played by Christopher Baker should be Group Captain James Stagg?
As far as I am aware there is no such rank as Group Capt. Maj (Group Captain Major). That appears to be a combination of a Royal Air rank and an Army one.
James Martin Stagg was a UK meteorologist who was given the rank of Group Captain in WWII. He later worked as Director of Services at the Meteorological Office until 1960.