William Beauclerk, 8th Duke of St Albans

Portrait of his father and mother, and his siblings Aubrey, Lady Catherine, and Lady Caroline, by Franciszek Smuglewicz.

William was born on 18 December 1766. He was the second son of Lady Catharine Ponsonby and Aubrey Beauclerk, 5th Duke of St Albans, a Whig Member of Parliament for Thetford from 1761 to 1768 and for Aldborough from 1768 to 1774. His elder brother was Aubrey Beauclerk, 6th Duke of St Albans (father of Aubrey Beauclerk, 7th Duke of St Albans). His younger brothers were Adm. Lord Amelius Beauclerk (principal Naval aide de camp to King William IV and Queen Victoria) and the Rev. Lord Frederick Beauclerk (Vicar of Kimpton, Redbourn and St Michael's who married Hon. Charlotte Dillon-Lee, the daughter of Charles Dillon-Lee, 12th Viscount Dillon). His sisters included Lady Catherine Beauclerk (wife of Rev James Burgess, Vicar of Hanworth), Lady Caroline Beauclerk (wife of Hon. Charles Dundas, fourth son of Thomas Dundas, 1st Baron Dundas).[2]

His father was eldest surviving son of Mary Chambers (eldest daughter and co-heiress of Thomas Chambers of Hanworth) and Vere Beauclerk, 1st Baron Vere (third son of Charles Beauclerk, 1st Duke of St Albans, himself the illegitimate son of Charles II of England and his mistress, Nell Gwyn). His mother was the eldest daughter of William Ponsonby, 2nd Earl of Bessborough and Lady Caroline Cavendish (eldest daughter of William Cavendish, 3rd Duke of Devonshire).[2]

He entered the Royal Navy in 1782 and was made a Lieutenant in 1788.[2]

On 20 July 1791, He married, firstly, Charlotte Thelwell (c. 1769–1797), the daughter and heiress of Rev. Robert Carter Thelwall of Redbourne Hall and Charlotte Nelthorpe (a daughter of Sir John Nelthorpe, 5th Baronet). Before her death on 19 October 1797, they were the parents of one child:[2]

• William Robert Beauclerk (1794–1794), who died in infancy.[2]

He married, secondly, Maria Janetta Nelthorpe (c. 1779–1822), on 4 March 1799. Maria was the only daughter and heiress of John Nelthorpe of Little Grimsby Hall (the former High Sheriff of Lincolnshire) and Mary Cracroft (second daughter, by his first wife, of Robert Cracroft of Hackthorn Hall). Before her death in 1822, they were the parents of thirteen children:[2]

• Lady Maria Amelia Beauclerk (1800–1873), who died unmarried.[2]
• William Beauclerk, 9th Duke of St Albans (1801–1849), who married Harriet Mellon and, after her death, Elizabeth Catherine Gubbins.[2]
• Lady Charlotte Beauclerk (1802–1842), who died unmarried.[2]
• Lady Caroline Janetta Beauclerk (1804–1862), who married Arthur Capell, 6th Earl of Essex.[3]
• Lord John Nelthorpe Beauclerk (1805–1810), who died in childhood.[2]
• Lady Louisa Georgiana Beauclerk (1806–1843), who married Thomas Hughan.[2]
• Capt. Lord Frederick Charles Peter Beauclerk (1808–1865), who married Jemima Johnstone.[2]
• Lady Georgiana Beauclerk (1809–1880), who married Sir Montague Cholmeley, 2nd Bt.[2]
• Lady Mary Noel Beauclerk (1810–1850), who married Thomas Corbett, MP for North Lincolnshire.[2]
• Lord Henry Beauclerk (1812–1856), who died unmarried.[2]
• Lord Charles Beauclerk (1813–1861), who married Laura Stopford and had issue. His son Aubrey Topham Beauclerk was the father of Charles Beauclerk, who in 1964 became 13th Duke of St Albans.[2]
• Capt. Lord Amelius Wentworth Beauclerk (1815–1879), who married Frances Harrison and had issue, including William Abdy Beauclerk.[2]
• Lord George Augustus Beauclerk (1818–1880), who died unmarried.[2]

The Duchess died on 17 January 1822. The Duke of St Albans died on 17 July 1825 and was succeeded by his son, from his second wife, William.[2]