She was born at Selkirk in the Scottish Borders to portrait painter Mary Winona Mannin "Molly" Bishop and Lord George Montagu Douglas Scott, the youngest son of the Duke of Buccleuch and Queensberry, Scotland's largest landowner (making her a niece to Princess Alice, Duchess of Gloucester).
After World War II her parents settled in Wiltshire, where Charmian grew up with two siblings, Georgina Mary "Gina" and David.
She went on to study briefly at the Chelsea School of Art, where she quickly realized she was not happy and left.
She then began modelling and found success until a car crash left her with minor facial injuries.
After moving to Stockwell, South London, she married Colin Campbell, a television executive, and became stepmother to his two daughters from his previous marriage.