Background
Erskine was the son of Lieutenant-General Sir Henry Erskine, 5th Baronet, and Janet, daughter of Peter Wedderburn (a Lord of Session under the judicial title of Lord Chesterhall) and sister of Alexander Wedderburn, 1st Earl of Rosslyn.
Erskine was the son of Lieutenant-General Sir Henry Erskine, 5th Baronet, and Janet, daughter of Peter Wedderburn (a Lord of Session under the judicial title of Lord Chesterhall) and sister of Alexander Wedderburn, 1st Earl of Rosslyn.
He was educated at Edinburgh High School and Eton, and was commissioned in the 21st Light Dragoons in 1778.
Erskine succeeded as sixth baronet in 1765 at the age of three on the death of his father. Erskine was assistant Adjutant-General in Ireland in 1782. In 1793 became Adjutant-General, in which capacity he served at the Siege of Toulon and Corsica.
In 1795 was promoted to colonel and appointed Aide-de-Camp to King George III. He became a major-general in 1798, lieutenant-general in 1805 and general in 1814.
He also saw action in Denmark
Initially a Whig, an adherent of Edmund Burke and an active supporter of Charles James Fox against William Pitt the Younger in the debates over the East India Company, he was one of the managers of the Impeachment of Warren Hastings. In 1796 was elected for the Dysart Burghs in Fife, a constituency traditionally under the Street Clair influence.
In 1829 he was sworn of the Privy Council. Lord Rosslyn married Harriet Elizabeth, daughter of the Honorary
Edward Bouverie, in 1790.
She died in August 1810. Rosslyn remained a widower until his death in January 1837, aged 74.
1st United Kingdom Parliament. 2nd United Kingdom Parliament]
In 1806 he was a member of the special mission to Lisbon, which resulted in Sir Arthur Wellesley (later the Duke of Wellington) being sent to the Peninsular. Erskine was a member of the House of Commons for the English pocket boroughs of Castle Rising between 1782 and 1784 and Morpeth between 1784 and 1796.
He was a member of the cabinet as Lord Privy Seal from 1829 to 1830 under the Duke of Wellington"s and Lord President of the Council under Sir Robert Peel from 1834 to 1835.