Isabel Diana Colegate, FRSL, who died 12 March, 2023, aged 91, was an author and literary agent, and a first cousin of HRH The Duchess of Kent.
Her novel The Shooting Party (1980) was adapted as an award-winning film of the same name, released in 1985 by Castle Hill Productions Inc. In 2010, it was adapted for radio by the BBC.
She was born 10 September, 1931, a daughter of Sir (William) Arthur Colegate (1884-1956), of Bembridge, Isle of Wight, a Conservative MP, by his wife the former Winifred Mary Worsley (1888-1955), daughter of Sir William Henry Arthington Worsley, 3rd Baronet (1861-1936), of Hovingham Hall, York.
She married in 1953, Michael Fenwick Briggs (1926-2017), son of Dennis Briggs, of Oxford. Their home from the early 1960s to 2007 was Midford Castle, Bath.
She leaves two sons, Barnaby and Joshua, and a daughter, Emily.