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 (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 Rosemary Parker Bowles (née Shand, born 17 July 1947) is the second wife of Charles, Prince of Wales, heir apparent to the thrones of the United Kingdom and the other 15 Commonwealth realms, and was his long-time partner before their marriage.
Edmonstone died at Edinburgh.
- Hansard 1803–2005: contributions in Parliament by William Edmonstone
|Parliament of the United Kingdom|
John Elphinstone Erskine
|Member of Parliament for Stirlingshire
1874 – 1880
Joseph Cheney Bolton
|Baronetage of Great Britain|
1871 – 1888