Gage was the eldest son of Joseph Gage of Sherborne Castle and Elizabeth Penruddock, the daughter and heiress of Sir George Penruddock. He succeeded his father-in-law to High Meadow in 1714. Under a marriage settlement dated 3 October 1713, he married Benedicta Maria Theresa Hall, daughter and heiress of Henry Benedict Hall of High Meadow, Gloucestershire and his wife Frances Fortescue. He converted to the Church of England in 1715, perhaps to enable him to sit in parliament.
Gage was elected MP for Tewkesbury at a by-election on 25 October 1721 and was elected again at the 1722 general election. In his first session of this parliament, he made several speeches against the special tax on Papists. In April 1727 he spoke for the motion for a vote of credit. He was returned again at the 1727 general election. He exposed the fraudulent sale of the Derwentwater estates on 31 March 1732, and was subsequently rewarded with £2,000 for this under the Greenwich Hospital Act 1735. At the 1734 general election, he was returned again as MP for Tewkesbury. He introduced a bill to prevent clandestine marriages, in 1736, but it was rejected. In 1738, it was rumoured that he was to be appointed as Governor of Barbados, but the appointment was never materialised, probably because he lacked sufficient political connections. He went into opposition with Pulteney in 1739, but in February 1741, he was one of the opposition Whigs who withdrew on the motion for Walpole's removal. He was returned to parliament again at the 1741 general election. On 23 April 1744, his cousin, Sir William Gage, 7th Baronet, died without children, and Gage inherited the baronetcy and the family estate of Firle Place. Sir William's late father was Gage's uncle - Sir John Gage, 4th Baronet, Sheriff of Sussex. The main line of the family, up to the 7th Baronet, had been Roman Catholic recusants who had purchased their baronetcy from King James I, and Gage quietly resumed practising Roman Catholicism, although his children were raised in the Church of England. At the 1747 general election, he was returned again for Tewkesbury and joined the opposition. In 1747 was appointed Steward of the Household of Frederick, Prince of Wales and held the post until 1751.
Later life
Gage's wife died on 25 July 1749, and on 26 December 1750 he married secondly Jane Godfrey, a Gloucestershire heiress. He had extensive remodelling work done on Firle Place and between 1743 and 1753, and was involved in a number of land rights disputes regarding windfall trees, soil rights, and manorial waste. Gage also spent considerable time collecting paintings which are still housed in the Long Gallery of Firle Place today. Gage and his son were defeated at the 1754 general election, having decided not to respond to the threats of his voters only to vote for candidates who promised to give £1,500 towards mending the roads.
