William Cowper - Temple , 1st Baron Mount Temple William Francis Cowper - Temple , 1st Baron Mount Temple PC ( 13 December 1811 – 16 October 1888 ) , known as William Cowper ( pronounced " Cooper " ) before 1869 and as William Cowper - Temple between 1869 and 1880 , was a British Liberal Party politician and statesman . Background and education . Born at Brocket Hall , Hertfordshire , Cowper was the second son of Peter Cowper , 5th Earl Cowper , and the Hon . Emily Mary , daughter of Peniston Lamb , 1st Viscount Melbourne ( since his mother had several lovers there is some doubt about hid true paternity ) . He was the younger brother of George Cowper , 6th Earl Cowper and nephew of Prime Minister Lord Melbourne . His father died in 1837 and in 1839 his mother married another Prime Minister , Lord Palmerston , who became Cowper ' s stepfather . He was educated at Eton . After entering the Royal Horse Guards in 1830 , he was promoted Captain five years later , eventually attaining the rank of Major in 1852 . Political career . In 1835 , Cowper was elected Liberal Member of Parliament for Hertford , a seat he held for the next thirty - three years , and became private secretary to his uncle Prime Minister Lord Melbourne . He was appointed a Groom in Waiting in 1837 , and in 1841 served for three months as a Lord of the Treasury under Melbourne , only resuming office five years later as a Lord of the Admiralty when the Whigs returned to power under Lord John Russell . He again held this post under Lord Aberdeen from 1852 to 1855 , and in the latter year was made Under - Secretary of State for the Home Department by his stepfather Lord Palmerston when he became Prime Minister . In August that same year he was appointed President of the Board of Health , and sworn of the Privy Council . Four years later he became Vice - President of the Board of Trade and Paymaster General , only serving for a year before Palmerston appointed him First Commissioner of Works . In 1866 , on the fall of Lord Russell ' s government , Cowper left office for good . Two years later he was returned to Parliament for Hampshire South , and held this seat until 1880 . He was involved in the 1870 Education Act which set up Board Schools throughout England . He was responsible for the Cowper - Temple clause , an amendment to the Act that allowed parents to withdraw their children from Religious Education . The British rock band Cooper Temple Clause were named after the clause . When his mother died in 1869 , he inherited a number of estates under his stepfather ' s will , and so took that year under Royal licence the additional surname of Temple . The properties included a 10 , 000 acre estate on Sligo ' s Mullaghmore peninsula with its unfinished Classiebawn Castle , commissioned by his stepfather , which he completed by 1874 . In 1880 he was raised to the peerage as Baron Mount Temple , of Mount Temple in the County of Sligo . This was a revival of the junior title held by the Viscounts Palmerston , which had become extinct along with the viscountcy on his stepfather ' s death in 1865 . Apart from his political career Lord Mount Temple organized ecumenical conferences at Broadlands . One of the regular speakers there was George MacDonald . Personal life . Lord Mount Temple was twice married . He married firstly Harriet Alicia , daughter of Daniel Gurney , in 1843 . After her early death the same year , he married secondly , in 1848 , Georgiana Tollemache , daughter of Admiral John Richard Delap Tollemache , and a sister of the 1st Baron Tollemache . Both marriages were childless . He died in October 1888 , aged 76 , at his home of Broadlands , Hampshire , and was buried at nearby Romsey . His peerage became extinct on his death . Lady Mount Temple died in October 1901 , aged 79 . His estates were inherited by his nephew , the Rt . Hon . Evelyn Ashley , the second son of Anthony Ashley - Cooper , 7th Earl of Shaftesbury .