My parents christened me Elizabeth and were adamant that my name would never be shortened. There are so many diminutives for it I've lost count. I don't mind Liz or Lizzie but I won't answer to Betty. Other variations include Bet, Beth, Lisbeth, Libby, Ellie and there's probably more. Small children always had trouble with Elizabeth so I got Bep-bep, Alushabush (shortened to Bush!) and Aluffafuff (shortened to Fuff). There were so many of us in my year at school (1952) that we all had a different form of Elizabeth to tell us apart.
I've gone by Liz since high school but my mother never called me anything but Elizabeth. My dad called me Liz the day and hour I turned eighteen! I was astonished! His theory was that I was now officially an adult and I could choose!
My late husband used to introduce me as Elizabeth, so people felt obliged to call me that. I kept having to say, call me Liz.... Elizabeth seems rather formal to me now.