William Petty-FitzMaurice, Earl of Kerry

Depiction of the House of Commons during Kerry’s time in Parliament. William Thomas Petty-FitzMaurice, Earl of Kerry (30 March 1811 – 21 August 1836), styled Earl of Wycombe between 1811–1818, was an Anglo-Irish aristocrat and Whig Member of Parliament for Calne, Wiltshire. He was the heir to his father, Henry Petty-Fitzmaurice, 3rd Marquess of Lansdowne, but died aged only 25.

Background Kerry was born at Lansdowne House, London, the eldest son of Henry Petty-Fitzmaurice, 3rd Marquess of Lansdowne, and Lady Louisa Emma, daughter of Henry Fox-Strangways, 2nd Earl of Ilchester. Thomas FitzMaurice claimed one of the two seats in 1762. In 1832, the borough was reduced to one member. Kerry was again returned unopposed in 1835 but died the following year.

He was succeeded by his mother's half-brother John Fox-Strangways.

Marriage, issue, and death Lord Kerry married Lady Augusta Lavinia Priscilla, daughter of John Ponsonby, 4th Earl of Bessborough, in 1834. They had one daughter:

Lady Mary Caroline Louisa (25 April 1835 – 17 September 1927), who married in 1860 Sir Percy Egerton Herbert, and was the mother of George Herbert, 4th Earl of Powis, and two daughters.

Following a lengthy illness, Kerry died at Lansdowne House, London, in August 1836, aged 25. The cause of death was constrictive pericarditis. In April 1837, Freeman's Journal reported that news from 7 April that she had given birth to a son were false, and that the earl's brother now was expected to become heir apparent, the countess apparently having suffered a late miscarriage or stillborn son. The following day, the newspaper reported that the Countess had "so far recovered from her late illness as to be able to take carriage airings."

Kerry's younger brother Lord Henry succeeded him as their father's heir apparent but chose to be styled as the Earl of Shelburne — another courtesy title to the Marquessate of Lansdowne — instead of the Earl of Kerry. In the 1837 general election, Shelburne was elected to his brother's old seat for Calne, which he held until 1856. He succeeded in the marquessate in 1863 upon the death of their father. She died in November 1904, aged 90.

Catherine, Princess of Wales

Research in 2012 suggested that Catherine, Princess of Wales (Kate Middleton), might be a collateral descendant of prime minister William Petty, 1st Marquess of Lansdowne (1737–1805), who is the grandfather of Lord Kerry. The connection might be through Lady Bullock, née Barbara May Lupton (1891–1974) who is the Princess's second cousin, thrice removed.