William Cowper-Temple, 1st Baron Mount Temple

William Francis Cowper-Temple, 1st Baron Mount Temple, PC (13 December 1811 – 16 October 1888), was a British Liberal statesman. He was born at Brocket Hall, Hertfordshire, as the second son of Peter Cowper, 5th Earl Cowper, and the Honorable Emily Lamb, sister of Lord Melbourne, Prime Minister. Due to uncertainties surrounding his paternity, there is some doubt about whether his biological father was Peter Cowper or one of Emily Lamb’s lovers. His elder brother was George Cowper, 6th Earl Cowper, and he was a nephew of Lord Melbourne, who served as Prime Minister.

In 1837, Cowper's father died, and two years later, his mother married Lord Palmerston, who became Cowper-Temple's stepfather. His education took place at Eton College. In 1830, he entered the Royal Horse Guards, achieving the rank of Captain in 1835 and brevet Major in 1852.

Cowper-Temple was elected as a Liberal Member of Parliament (MP) for Hertford in 1835, a seat he held until 1868. During his time in Parliament, he served as private secretary to his uncle, Prime Minister Lord Melbourne. His early government roles included a brief stint as a Groom in Waiting in 1837 and serving as a Lord of the Treasury under Lord Melbourne in 1841. When the Whigs returned to power under Lord John Russell in 1846, Cowper-Temple resumed government service as a Lord of the Admiralty until 1852. He served as a Lord of the Admiralty again under Lord Aberdeen from 1852 to 1855, and in 1855, he was appointed Under-Secretary of State for the Home Department by his stepfather, Lord Palmerston, who was then Prime Minister. That same year, he was appointed President of the Board of Health and was sworn into the Privy Council.

In 1859, Cowper-Temple became Vice-President of the Board of Trade and Paymaster General, serving for about a year before being appointed First Commissioner of Works by Palmerston. Following the fall of Lord Russell's government in 1866, he left office. He was elected MP for Hampshire South in 1868, a position he held until 1880.

Cowper-Temple played a significant role in the 1870 Education Act, which established Board Schools (state primary schools managed by locally elected school boards) across England. He was responsible for the Cowper-Temple clause, an amendment (Section 14 of the Act) that mandated non-denominational religious instruction in these schools and provided parents the right to withdraw their children from religious classes. Section 7 of the Act further allowed parents to withdraw children at any time for religious reasons.

In 1869, upon the death of his mother, Cowper-Temple inherited multiple estates under the will of his stepfather, including a large estate on Sligo’s Mullaghmore Peninsula and the unfinished Classiebawn Castle, which he completed by 1874. That year, he adopted the additional surname "Temple" by Royal license.

In 1880, Cowper-Temple was elevated to the peerage as Baron Mount Temple, of Mount Temple in County Sligo. This peerage was a revival of the title held by the Viscounts Palmerston, which had become extinct with his stepfather’s death in 1865. He also organized ecumenical conferences at Broadlands, frequently inviting speakers such as George MacDonald.

He married twice but had no children. His first marriage was in 1843 to Harriet Alicia Gurney, who died the same year. His second marriage, in 1848, was to Georgina Tollemache, daughter of Admiral John Richard Delap Tollemache; this marriage also remained childless.

William Cowper-Temple died on 16 October 1888 at Broadlands, Hampshire, at the age of 76, and was buried at Romsey. His peerage became extinct upon his death. Lady Mount Temple died in October 1901 at age 79. His estates were passed to his nephew, Evelyn Ashley, son of Anthony Ashley-Cooper, 7th Earl of Shaftesbury.

His name was associated with the SS Mount Temple, a Canadian Pacific passenger ship launched in 1901, and the British rock band The Cooper Temple Clause.