Oil on canvas, 89.5cm by 69.2cm.
Signed l.r.: Mary Kammerer/1929.
Lady Mary Theresa Montagu Douglas Scott was a daughter of the 7th Duke of Buccleuch and the first wife of David, Lord Burghley, later 6th Marquess of Exeter (1905-1981). They were divorced in 1946.
The artist was born Maria ‘de’ Kammerer in Budapest, Hungary. She later became an American citizen and seems to have been known thereafter as either Maria, or Mary Kammerer.