Anstruther was born about 1680, the only son of Sir Philip Anstruther of Airdrie and his wife Katherine Skene daughter of John Skene of Hallyards, Fife. His father died in 1682. He joined the army and was a Captain and Lieutenant-colonel in the 1st Foot Guards in 1710.
Career
Anstruther was returned unopposed as Member of Parliament for Anstruther Burghs at the 1715 general election. He was still an active army officer and was made colonel of the 26th Foot in 1720 holding the rank until his death. At the 1722 general election there was a contest at Anstruther with a double return, but he was declared elected on 27 October 1722. He was returned at Anstruther unopposed at the general election in 1727. In 1733 he was appointed Lieutenant-governor of Menorca, but was still returned unopposed as MP for Anstruther at the 1734 general election. Anstruther became a brigadier-general in 1735. His only vote in the 1734 Parliament was in 1737, when he was the only Scottish MP to support government reprisals against Edinburgh over the Porteous Riots. This made him an object of detestation among his countrymen and rendered it difficult for him to go about Edinburgh openly. He became a major-general in 1739 but in 1741 was called before the House of Lords to explain his long absence from duty and the poor morale among his troops in Menorca. He had been defeated at the 1741 general election and received no support from his colleagues for a petition. After his return to Menorca, in 1742 he court-martialled his subordinate, Henry Erskine, for a supposed conspiracy against him. Erskine was acquitted but remained his bitter political enemy. During the Forty-five Rebellion, Anstruther served under General Ligonier and became a Lieutenant-General. However by 1747 his military command at Menorca was incompatible with holding a seat in the House of Commons, and he resigned to stand for Anstruther Burghs at the 1747 general election. Anstruther was returned as MP for Anstruther Burghs but much of his time in Parliament was spent defending his activities at Menorca. A report of a committee of the Privy Council concluded he "in many instances acted in an arbitrary and unwarrantable manner to the great injury and oppression of many of your Majesty's subjects there in breach of his duty to your Majesty and contrary to the constitution of the island." He was also under attack from Erskine, now in Parliament. Erskine decided to attack him directly by standing for Parliament at Anstruther Burghs in the 1754 general election. Defeated by Erskine, Anstruther, at the age of 74, did not petition.
