Cary was the son of Lucius Cary, 2nd Viscount Falkland and his wife Lettice Morison, daughter of Sir Richard Morison of Tooley Park, Leicestershire. He was educated at Hayes, Middlesex under Dr Thomas Triplett. He inherited the title Viscount Falkland after his brother Lucius Cary died in 1649 and travelled abroad in France in 1650. Cary like his father and elder brother, had Royalist sympathises and during the early years of the Interregnum his movements were monitored by the Council of State, but after William Lockhart of Lee, the Protector's ambassador in Paris, had assessed him, he was no longer perceived to be a serious threat to the new establishment. In 1659, Cary was elected Member of Parliament for Oxfordshire in the Third Protectorate Parliament where he opposed recognition of the Other House. During the second Commonwealth period he sided against the Officers in charge of the New Model Army in London and was arrested for involvement in the proposed 1659 Royalist rising and sent to the Tower of London. In February 1660 he threw himself behind General George Monck when with other Oxfordshire gentry signed a declaration calling for a free parliament. The next month he was appointed justice of the peace and a commissioner for the militia for Oxfordshire. Cary was returned as Member of Parliament for both Oxford and Arundel and chose to sit for Oxford in the Convention Parliament. He was an active in this parliament supporting Anglican and Royalists cause, and he was selected as one of the twelve members chosen to visit King Charles II in Holland and returned across the channel with the King. While Charles was in Canterbury, Cary returned to London carrying a letter from the King to Parliament. During the debates over the Indemnity and Oblivion Bill Cary "took a strong line towards the regicides, and argued that any member who had sat in the high court of justice should be excluded from the house. Regarding individual parliamentarians, he wished to make William Sydenham and John Pyne liable for any penalty short of death, and he opposed the limited punishment proposed for Francis Lascelles." In June 1660, shortly after the Restoration of King Charles II Cary was made a colonel of horse and gentleman of the privy chamber. From then until his sudden death in 1663 he was active at court and Royal service. In 1661 he was elected Member of Parliament for Oxfordshire in the Cavalier Parliament as well as holding various military commissions. He supported the crown during the debates on the Militia Bill that affirmed the crown's powers over the armed forces, but was in disfavour with some at court over his ardent support for the Act of Uniformity making clear his dislike of both Catholics and dissenters and not accepting the government's line that tolerance should be shown. In 1661 he was appointed colonel of foot in the Dunkirk garrison. In August 1662 he was elected to the Irish parliament for Fore and spent some time there, and in October 1662, after his regiment was disbanded, he was appointed captain of a troop of horse in Ireland. The same month he returned to London to resume his work on committees in the Commons. Cary was the author of the playThe Marriage Night. Set in Castile it had themes of tragedy and revenge, of which Samuel Pepys wrote in his diary after seeing it "a kind of a tragedy, and some things very good in it, but the whole together, I thought, not so" . Cary died at the age of about 29 and was buried at Great Tew.
