John Gage was born on 28 October 1479 at Burstow manor in Surrey and baptized at the parish church there on the same day. He was the only son of William Gage and Agnes Bolney. He married Philippa Guildford, daughter of Sir Richard Guildford, on 14 April 1502. They were the parents of eight children:
An Esquire of the Body to both Henry VII and Henry VIII, he served offices in the Pale of Calais, becoming Comptroller in 1524. After receiving a knighthood in 1525, he moved to the post of Vice-Chamberlain of the Household in 1526, leaving court in 1533. He also represented Sussex three times in the parliaments of Henry VIII. He remained active, attending, in 1537, the baptism of Prince Edward and the funeral of Jane Seymour. He returned to favour, and 1540 saw his appointment as Comptroller of the Household, Constable of the Tower and as a Privy Counsellor. In his role as Constable of the Tower, he supervised the arrangements for the execution of Catherine Howard. In 1541 he became a Knight of the Garter and in 1542 he succeeded as Chancellor of the Duchy of Lancaster. In 1544 he undertook an important role for the invasion of France, organising transport and supplies for the army, and he became a knight banneret. Present at the funeral of Henry VIII, he was appointed one of the executors of the king's will and a member of Edward VI's Regency Council. Differences soon arose between him and The Duke of Somerset, who expelled him from the council and from his posts of Comptroller and Chancellor when he became Lord Protector in 1547. He re-joined the council, before resigning upon the accession to power of The Earl of Warwick, later Duke of Northumberland. He was suspended as Constable for not supporting Northumberland's attempt to install Lady Jane Grey as Edward's successor. The accession of Mary I saw his restoration as Constable and appointment as Lord Chamberlain. He bore her train at her coronation and at her marriage to Philip of Spain. As Constable, he guarded Princess Elizabeth in 1555; he was described by Heylyn as "her bitter enemy, but more for love of the Pope than for hate of her person".
Death
Gage died at his house, Firle Place, on 18 April 1556, and was buried on 25 April at West Firle Church next to his wife. Their alabaster altar tomb in the north chapel of that church is the work of Gerard Johnson the elder and, along with monuments for some other members of their family, was erected in about 1595. His will, made on 20 February 1555/6, was proved at the Prerogative Court of Canterbury on 10 June 1556. A lengthy and detailed household inventory was added as a schedule to the will and points to the wealth and lifestyle that Sir John enjoyed. An introduction and transcription of the inventory has been published.
