 Robertson was Liberal Member of Parliament for Dundee from 1885 to 1908, and held office under Gladstone and Lord Rosebery as Civil Lord of the Admiralty from 1892 to 1895 and under Sir Henry Campbell-Bannerman as Parliamentary Secretary to the Admiralty from 1905–1908.He was appointed a Privy Counsellor in 1905 and raised to the peerage as Baron Lochee, of Gowrie in the County of Perth, in 1908.Lord Lochee died in September 1911, aged 65, when the barony became extinct.