Born at Hampton, Edmonstone was Member of Parliament for Stirlingshire from 1874 to 1880, and an Aide-de-Camp to Queen Victoria. He married at Zakynthos, Greece, on 13 July 1841, Mary Elizabeth Parsons (Newburn, Fife, 21 June 1823 – Cramond House, Midlothian, 11 August 1902), daughter of Lieutenant-Colonel C. M. G. Parsons, who was British Resident on the island of Zante, at a time when the Ionian Islands were a British Protectorate. Mary Elizabeth and Sir William in all had eleven children, nine of whom survived into adulthood:
- Mary Emma Frances (1842–1847), died when she was five
- Archibald Edmonstone, died in infancy; their second son (see below) bore the same name.
- Jessie Edmondstone (d. 10 June 1937)
- Louisa Ann Edmonstone (d. 3 July 1921)
- Charlotte Henrietta Edmonstone (d. 21 October 1931)
- Frances Euphemia Edmonstone (d. 14 February 1921)
- Sophia Edmonstone (d. 19 February 1924)
- Susanna Emily Edmonstone (d. 9 May 1886)
- Mary Clementina Edmondstone (1857 – 2 December 1922)
- Sir Archibald Edmonstone of Duntreath, 5th Bt. (30 May 1867 – 1 April 1954)
- Alice Frederica Edmonstone (29 April 1868 or 14 October 1869 – 11 September 1947), a British socialite and one of the many mistresses of Edward VII of the United Kingdom; her great granddaughter Camilla, Duchess of Cornwall (née Shand, born 17 July 1947) is the second wife of Charles, Prince of Wales.
Edmonstone died at Edinburgh.
- O'Byrne, William Richard (1849). " Edmonstone, William". A Naval Biographical Dictionary. John Murray. Wikisource.
- Hansard 1803–2005: contributions in Parliament by William Edmonstone
|Parliament of the United Kingdom|
John Elphinstone Erskine
|Member of Parliament for Stirlingshire
Joseph Cheney Bolton
|Baronetage of Great Britain|