In 1841 he had only just been elected to the House of Commons for Wilton as a Conservative, when his father died and he succeeded to the peerage. Malmesbury served as Foreign Secretary under the Earl of Derby in 1852 and again from 1858 to 1859 and was also Lord Privy Seal under Derby and Benjamin Disraeli between 1866 and 1868 and under Disraeli between 1874 and 1876. In 1852 he was admitted to the Privy Council. He was regarded as an influential Tory of the old school in the House of Lords at a time when Lord Derby and Disraeli were, in their different ways, moulding the Conservatism of the period.