"Dressing Rooms" for rich Englishmen in the '20s

I was just looking at a picture of Dunster Castle (offline), and the servants bells caught my eye. From the Dressing Room, from the other dressing room, and from the other dressing room. I don’t have access to the picture for more detail.

The home was occupied and updated in '20s until WWII. The servant bells probably date from then. It would have hosted hunting and shooting parties in the 1920’s and 30’s

What exactly was a ‘dressing room’? Why did the home require 3 or more of them? Who used them, when, and why?

Historically, they provided medieval ladies of the manor with a degree of privacy in houses which were full of servants and extended family members.

‘They evolved in larger homes where much of the living space was shared in a great hall,’ says Melanie Backe-Hansen, author of House Histories: The Secrets Behind Your Front Door. ‘They were in addition to the bedroom, and men and women had their own.’

After becoming popular in middle-class homes during the Victorian era, the dressing room gradually fell out of favour in the 20th century. With the emergence of the nuclear family, and the decline in the number of live-in servants, finding ‘a room of one’s own’ no longer meant retreating to a dedicated dressing chamber.