Mary Montagu was the second daughter and coheir of the 2nd Duke of Montagu. She married the 4th Earl of Cardigan (later Duke of Montagu) in 1730. This was painted in Bath, and according to Waterhouse from the same sittings as the three-quarter length of the Duchess at Bowhill. However, this portrait, in which the Duchess wears different clothes and appears older, may be a little later.
PROVENANCE by descent from the sitter