The sitter was the wife of Sir John Bankes (1589-1644), attorney general and chief-justice of the common pleas. In 1635 they purchased Corfe Castle in Dorset which became the family seat. In 1643, at the outbreak of the Civil War, Sir John Bankes was impeached by Parliament and Lady Bankes came under attack at Corfe Castle by Parliamentarian forces led by Sir Walter Erle, a Dorset neighbour. She successfully defended her home with, according to the inscription on the reverse of the miniature, 'a Garrison never exceeding 40', and Erle finally retreated after a siege lasting almost two months. On the death of Sir John Bankes in 1644, Mary was faced with financial difficulties and her home came under attack again, this time by Cromwell's parliament who ordered her to hand over or sell assets to settle her tax bill. Her attempts to defend the family home through diplomatic means were thwarted by a further siege on Corfe Castle by Parliamentarian forces led by another Dorset neighbour, Colonel Bingham, in 1645 and the penetration of the castle by soldiers disguised as Royalist troops. The castle was stripped of its furnishings and was subsequently destroyed. Mary was awarded the keys of the castle by Colonel Bingham in recognition of her bravery and they were later enshrined at the family's new home at Kingston Lacy, Dorset, now owned by the National Trust. An oval enamel miniature of Lady Mary Bankes holding the keys to Corfe Castle by Henry Pierce Bone and a rectangular enamel by Henry Bone, dated 1821, framed with a portrait of Sir John Bankes, are in the National Trust Collection at Kingston Lacy. The preparatory drawing by Henry Bone, which was probably also used by Henry Pierce Bone for the present portrait, is in the National Portrait Gallery (inv. no. NPG D17242), see R. Walker, 'Henry Bone's Pencil Drawings', The Walpole Society, LXI, 1999, p. 313, no. 26, illustrated fig. 100, the finished miniature of Lady Mary and Sir John Bankes, and counter-enamels, illustrated figs. 104, 103 and 102, respectively. The current location of the original miniature by John Hoskins, formerly at Kingston Lacy, is unknown.