Thomas was born in 1691, the seventh son of William Cochrane of Ochiltree, and his wife Lady Mary Bruce, eldest daughter of Alexander Bruce, 2nd Earl of Kincardine. As a younger son, he would not inherit his father"s property, so he entered the army.
He served as Commissioner of the Excise for Scotland from 1730 until 1764. He became a cornet in the Royal Regiment of Dragoons in 1713, and a captain in the 27th Regiment of Foot in 1716. He rose to the rank of major in 1718 and was Fort Major at Fort Street Philip on Minorca.
He was appointed as Commissioner of the Excise for Scotland from 1730 until 1764.
He supported the Hanoverians during the Jacobite Rising of 1745. He later gave evidence in court against Archibald Stewart, the Lord Provost of Edinburgh, who had surrendered the city to the Jacobites.
William, an army officer, had been killed at the Siege of Louisbourg, and died without issue. As the eldest surviving son by then of William Cochrane of Ochiltree, Thomas had already inherited the family estates at Culross and Ochiltree.
6th Parliament of Great Britain]
He was Member of Parliament for Renfrewshire, 1722-1727. He became Member of Parliament for Renfrewshire in 1722, and represented the constituency until 1727.
