Lockhart-Ross was also a wealthy landowner whose mother had bequeathed him large estates in both Lanarkshire and Ross-shire, the latter giving him control of the Royal Burgh of Tain.He was elected at a by-election in June 1786 as the Member of Parliament for the Tain district of Burghs and was re-elected in the 1790. In 1796 he was returned for Ross-shire, which returned him again in 1802. At the 1806 election he was returned for the Linlithgow Burghs, where he was defeated in 1807.[1]
He married twice, first in 1788 to Matilda Theresa, daughter of James Lockhart-Wishart of Lanarkshire, a Count of Holy Roman Empire and officer in the Austrian army. After her death in 1791 he married again in 1799, to Lady Mary Rebecca Fitzgerald, daughter of the 2nd Duke of Leinster.[1] He had a son, who died young, and a daughter in the first marriage and two sons and five daughters in the second. He was succeeded by his son, Sir Charles William Frederick Augustus Lockhart-Ross, 8th Baronet.