Birdie Boswell is the mother of Polly Shelby and grandmother of the Shelby siblings and the Gray siblings. She married a Shelby who's Polly Shelby's father.
Polly tells her son Michael Gray that his grandmother was a Gypsy Princess. Polly tells Ruben Oliver that her mother stole the expensive dress from a house she was cleaning in 1901. She and Bethany Boswell, who is the wise Gypsy, have the same surname.
The Boswells were for centuries one of England's largest and most important Gypsy families. The Boswell clan were a large extended family of Travellers, and in old Nottinghamshire dialect the word bos'll was used as a term for Travellers and Romani in general.