Jerningham was the representative of one of the few remaining families of English Gentry prior to the Conquest, and was descended on many sides from King Edward III.[2]
Upon the death of his father on 21 January 1774, he succeeded as the 7th Baronet Jerningham.[3] On the death of Lady Anastasia Stafford-Howard in 1807, he would have become the 7th Baron Stafford but for the attainder, which was reversed by his son in 1824.[4]
Personal life
On 16 June 1767, Sir William married the Hon. Frances Dillon (c. 1747–1825), daughter of Henry Dillon, 11th Viscount Dillon and Lady Charlotte Lee (a daughter of the 2nd Earl of Lichfield).[3] The Dillon family also had a strong Jacobite heritage.[5] Together they were the parents of:[1]
William Charles Jerningham (1772–1820), an Officer in the Austrian service who married Anne Wright, daughter of Thomas Wright, in 1803. After her death, he married Anne Moore, daughter of Edward Moore, in 1816.[1]
Edward Jerningham (1774–1822), a barrister who served as Secretary for British Catholic Board who married Emily Middleton, daughter of Nathaniel Middleton, in 1804.[1]
Sir William died at his seat, Costessey Hall in Norfolk, on 14 August 1809.[8] His youngest son Edward designed the St. Augustine Chapel at the family seat which opened the week after his death in 1809.[9]