Edward Stanley, 15th Earl of Derby

After the fall of the Russell government in 1866 he became Secretary of State for Foreign Affairs in his father's third administration. He compared his conduct in that great post to that of a man floating down a river and fending off from his vessel, as well as he could, the various obstacles it encountered.[3] He enunciated the policy of Splendid isolation in 1866:

it is the duty of the Government of this country, placed as it is with regard to geographical position, to keep itself upon terms of goodwill with all surrounding nations, but not to entangle itself with any single or monopolizing alliance with any one of them; above all to endeavor not to interfere needlessly and vexatiously with the internal affairs of any foreign country."[6][7]

Passport for a railway engineer dated 1876 containing Lord Stanley's full title and his signature.

He arranged the collective guarantee of the neutrality of Luxembourg in 1867, likely to be a theatre of war with the conflict between France and Prussia growing ever more likely. He also negotiated a convention with the USA about the CSS Alabama, which, however, was not ratified, and refused to take any part in the troubles in Crete.[3]

In 1874 he again became Foreign Secretary in Disraeli's government.[3] In 1875 came the purchase of the controlling shares in the Suez Canal Company. By negotiations, Russia gave up substantial gains in the Balkans and a foothold in the Mediterranean. Britain gained control of Cyprus from the Ottomans as a naval base covering the Eastern Mediterranean. In exchange, Britain guaranteed the Asiatic territories of the Ottoman Empire. Britain did not do well in conflicts in Afghanistan and South Africa.[8]

Derby acquiesced in Disraeli's purchase of the Suez Canal shares, a measure then considered dangerous by many people, but ultimately most successful. He accepted the Andrassy Note, but declined to accede to the Berlin Memorandum.[3] Derby's conduct during the Eastern Crisis was mysterious to many of his contemporaries and for some time thereafter. Derby's hope for peace with Russia led him (and his wife) to share Cabinet secrets with the Russian ambassador, Pyotr Shuvalov, in hopes of averting war with Russia.[9] Robert Blake commented that "Derby surely must be the only Foreign Secretary in British history to reveal the innermost secrets of the Cabinet to the ambassador of a foreign power in order to frustrate the presumed intentions of his own Prime Minister." Derby resigned in January 1878 when the Cabinet resolved to send the British fleet through the Dardanelles, but when that action soon proved unnecessary, Derby was allowed to withdraw his resignation. However, he resigned again and finally in the same year when the Cabinet agreed to call up the reserve.

By October 1879, it was clear enough that he had thrown in his lot with the Liberal Party, but it was not till March 1880 that he publicly announced this change of allegiance. He did not at first take office in the second Gladstone government, but became Colonial Secretary in December 1882, holding this position till the fall of that government in the summer of 1885. In 1886 the Liberal party split; Lord Derby became a Liberal Unionist, and took an active part in the general management of that party, leading it in the House of Lords till 1891, when Lord Hartington became Duke of Devonshire. In 1892 he presided over the Labour Commission.[3]

He succeeded his father as Honorary Colonel of the 1st Lancashire Rifle Volunteer Corps (1st Volunteer Battalion, King's (Liverpool Regiment) from 1888), being appointed on 21 September 1870. After his death he was succeeded by his son in turn.[10]

He served as President of the first day of the 1881 Co-operative Congress.[11]

• Derby, Edward Henry Stanley. Disraeli, Derby, and the Conservative Party: Journals and Memoirs of Edward Henry, Lord Stanley, 1849–1869 (Harvester Press, 1978)