Following her death last year at the age of 87, the belongings of Lady Spencer (1929-2016) will be offered at a Christie’s auction next month.
The saleroom said Lady Spencer enjoyed a position at the centre of London society for over 60 years, having been named Debutant of the Year in 1947.
Her collection includes fine and decorative arts, from Old Master paintings to clocks and jewellery.
She was particularly fond of 18th century French art and she assembled a collection of paintings by the likes Boucher, Fragonard and Vernet.
Highlights of her Old Master paintings will be offered for sale at Christie’s King Street on July 6 as part of the Old Masters Evening Sale. This will be followed by a dedicated collection sale on July 13.
The only child of Alexander McCorquodale and romantic novelist Cartland, she was a politician and socialite. She married the 9th Earl of Dartmouth in 1948, and in 1954, at the age of 23, she became the youngest member ever to be elected to Westminster City Council.
One of her notable triumphs came in the early 1970s when she helped prevent the redevelopment of Covent Garden.
Following their divorce, she went on to marry John Spencer, 8th Earl Spencer, in 1976 and became stepmother to his children, including Diana, Princess of Wales.
She was later criticised for her part in the £2m redecoration of the Spencer family seat of Althorp and the sell-off of many of the works of art from the estate.
Later, Charles Spencer, the 9th Earl, estimated that between his father’s re-marriage in 1976 and his death in 1992, some 20% of Althorp’s contents were sold.