Arabella Diana was the daughter of Sir Charles Cope, Bart. and in 1790 was married to John Frederick Sackville, 3rd Duke of Dorset. They had three children: Lady Mary Sackville (1792 – 1869); George John Frederick Sackville, styled Lord Middlesex, (1793 – 1815); and Lady Elizabeth Sackville (1795 – 1870).
On the death of her husband she retained control of the Sackville estates and thus the ownership of the Manor of Bexhill. Therefore from 1799 until 1870 Bexhill Manor was run by the female line; first Lady Arabella, then Lady Mary and finally Lady Elizabeth.
It was through Lady Elizabeth Sackville, who had been married to George John West, 5th Earl De La Warr, in 1813, that Bexhill Manor came to be owned by the West family. In 1843 the family names were amalgamated and became Sackville-West. When the 7th Earl succeeded to the title the name ‘West’ was dropped.