My wife bought a domestic ticket today in connection with her employment. The on-line booking offered her secretary a standard fare and an option to upgrade to a fully flexible ticket. Perhaps a C is shown on only the fully flexible ticket to indicate executive lounge access. I do not know I am just guessing. I will look at my wife's ticket to see what the class is shown on her e ticket when she gets home from work.
The class of travel on the booking system is shown as UK Domestic.
Perhaps someone who works in reservation can explain why C is shown on tickets if that does not indicate Club. One thing is for sure there is no seperated club cabin on any of the domestic services and has not been since the shuttle type services operated.