She was the second wife of Peregrine Bertie, 3rd Duke of Ancaster and Kesteven.

She was the daughter of Thomas Panton of Newmarket (1697–1782), who was an equerry to King George II and master of the Thurlow Hunt,[1] and his wife Priscilla (though she may have been illegitimate).

They had six children:[2] Following her marriage to the duke, Mary Panton's father Thomas obtained the post of Master of the King's Running Horses,[3] and his son, also Thomas, later inherited this position.

A watercolour miniature, by John Smart, dating to 1763, is held by the Nelson-Atkins Museum of Art.

On the birth of the future King William IV of the United Kingdom, the duchess recommended as wet-nurse a woman called Sarah Tuting, who was later acknowledged as her father's mistress.