Born in 1915, Marjorie Cox attended Miss Beatrice Flower's Art School and Heatherley's Art School in London. She became a noted portrait artist of animals, particularly of dogs, and travelled to certain parts of the country with paper and pastels once she had generated enough commissions in that area (she required her clients to transport her as she did not drive).
Patrons of Cox included Lady Southwell, Lady Tavistock, Peter Dimmock, Phil Drabble and Nancy Fenwick, who looked after the Queen's dogs. She painted seven of the Queen's dogs for Mrs. Fenwick, corgis, dachschunds and a 'dorgi'.