James Alexander St Clair-Erskine was the son of Sir James St Clair-Erskine Bt, 2nd Earl of Rosslyn, born on 15 Feb 1802. His mother was Harriet Elizabeth née Bouverie. Young James was styled Lord Loughborough in 1805, a title that lasted until 1837 when he inherited the earldom from his father. The 2nd Earl Rosslyn was Colonel of the 9th Lancers from 1801 to 1837 during which period, Lord Loughborough was Commanding Officer, from 6 March 1828 until 28 January 1842.
The 3rd Earl of Rosslyn was married to Frances Wemyss, daughter of Lieutenant General William Wemyss from Fife. They married in 1826 and had three children. Their first child, born in 1830 died young, at the age of 21; the second was Lady Harriet Elizabeth St Clair-Erskine born in 1831, and the third was Francis Robert St Clair-Erskine, born in 1833, who became the 4th Earl of Rosslyn.
1802 Born 15 Feb
1819 Cornet 9th Light Dragoons 25 Feb
1821 Lieutenant 47th Foot 13 Sep
1823 Captain 9th Lancers 22 May
1826 Major 9th Lancers 12 Dec
1827 Lieutenant-Colonel, Half Pay, unattached 31 Dec
1828 Lieutenant-Colonel 9th Lancers 6 Mar
1830 MP for Dysart Burghs
1831 MP for Grimsby
1837 Became 3rd Earl of Rosslyn 18 Jan
1841 Privy Council
1841 Master of the Buckhounds until 1846
1841 Colonel 23 Nov
1852 re-appointed Master of the Buckhounds
1854 Major-General 20 June
1859 Lieutenant General 26 Dec
1859 Under Secretary of State for War
1860 Commanded Fife Mounted Rifle Volunteers
1864 Colonel of 7th Hussars 27 Dec
1866 Promoted to General 20 April
1866 Died 16 June
