St John was a son of
Oliver St John, 3rd Baron St John of Bletso and his wife Dorothy Reid, daughter of Sir John Rede or Reid, of
Odington,
Gloucestershire. He was admitted
fellow commoner at
Queens' College, Cambridge on 9 March 1609/10, and was conferred an
MA in 1612/3, on the occasion of the King's visit. On 5 May 1613, he was admitted to
Lincoln's Inn. He was knighted on 24 July 1619 at Bletsoe together with his brother
Henry, later an MP. Apart from Henry, four other brothers,
Oliver,
Rowland,
Anthony and
Alexander were all to become MPs. In 1621 St John was elected
Member of Parliament for
Bedfordshire. He was elected MP for
Bedford in 1626 and again in 1628. He sat until 1629 when King Charles decided to rule without parliament for eleven years. In 1625 he inherited through his wife the manor of
Tilbrook. In April 1640, St John was elected MP for Bedford in the
Short Parliament. He was re-elected for Bedford for the
Long Parliament in November 1640, where he was active at least in 1643 and remained in support of the parliamentary cause. St John on 13 October 1613 married Rebecca Hawkins the daughter of William Hawkins of Tilbrook. They had a son, who died young, and a daughter. His elder brother
Oliver inherited the
Barony and became
Earl of Bolingbroke. ==References==