Educated, like his five uncles, at Queens’, Cambridge, St. John was presumably the man of this name granted a passport for the Continent in June 1617.
Heir to the family estates, St. John was matched with a daughter of the earl of Bridgewater in 1623. The dowry must have been substantial, as his wife received a generous jointure settlement.
Re-elected in 1626, St. John was appointed to the committee for privileges on 9 February. His membership of this body probably explains why he was also included on the committee to consider the punishment of the sheriff of Leicestershire, who had been found guilty of misconduct at the county election (26 April). With the exception of two estate bills (15 Feb., 13 Mar.) and the adultery bill (4 Mar.),
St. John found himself in trouble within hours of the dissolution of 15 June, when he was one of five MPs called upon to surrender his copy of the Remonstrance the Commons had passed two days previously. If he complied with this instruction he had the presence of mind to keep another copy of this document, which remains in the family papers.
In view of his family’s opposition to the Loan, it is surprising that St. John took little part in formulating the Petition of Right in 1628: he was named to attend only a single conference with the Lords on this issue (23 April).
Although St. John joined his father in draining the Great Level in the 1630s,
In December 1638 St. John assigned the estates in which he had a life interest to his father, and attempted to flee abroad under a false passport. Delayed by illness at Rye, he was arrested under a warrant from secretary Sir Francis Windebanke†, but he subsequently either escaped or was allowed to proceed, as he spent the next two years in exile.
