Apparently Blair was used in the Victorian era as a nickname for Elizabeth. Similarly to how Sadie was used for a nickname for Sarah. How does that work??
Jessica Emily Faith Living in the land of Oz... Ronan: For the sake of spicy, little boys wearing plaid shirts, running around in kneeless jeans, playing in the mud and being mischievous. Combo Considerations:
★Adela Meret ★ James Logan★ Jessie Pearl ★Everett Michael★ Winnie Noelle★ Elias Henry
Well, according to the wikipedia entry for Elizabeth, Blair is the Scottish nickname taken from the last part of Elizabeth. So I guess it somehow developed from Beth? *shrug* That's the only thing I could turn up in my five minutes of google research.
Blair is originally a masculine name and is from a Scottish last name, which is derived from the Gaelic blar, meaning plain, field, battlefield. It has no connection to Elizabeth. The closest Blair form from Elizabeth is Beileag, which isn't pronounced Blair!