Oh, I don't know - this may have been Mrs Bertie's choice. When I was growing up in about that era, we were required to call the people who worked for us by title and surname, and they just used our first names. Except for one dear gamekeeper, who became a great friend when I was about 17 or so (oh dear, that does sound Lady Chatterley-esque, but actually, not - his then mistress and subsequent wife was always there. I used to bum cigarettes off them both!), whom I then addressed by his nickname, and he always, but always, called me "Miss (firstname)". He drove us on our wedding day between the Church and the Reception, and address me as "Miss (firstname)", whereupon I pointed out that this was now incorrect, as I had been, for the last 15 minutes, Mrs So-and-so, and he could call me that if he insisted, or, preferably, just use my name!

But the point is, my parents required that sort of courtesy from us, not from their employees!