I'm writing about two 18 year old girls called Margaret (known as Peggy in childhood, at least) and Susan, living in England in 1937/8. What nicknames might a fashionable, rather empty-headed group of girls call them by? (I'm thinking of something along the lines of the part in Little Women where Meg is nicknamed Daisy by the Moffats when she visited them, to give you a better idea - names that would make them roll their eyes somewhat).
Another question I have is if Peggy would call herself that as an adult, or if it would be seen as a child's name?
For the first question, I Googled "margaret/susan nicknames 1930 england", and variations thereof; I also looked at behindthename.com's popularity statistics, but they don't have those for nicknames.
For the second, I googled "peggy nickname child/adult/childish".
Thank you for any help!
ETA: Thank you so much for all your answers! You've been really helpful, I have lots to work with now :)