On 27 Jan 1631 Johanna St John Baroness St John Lydiard Tregoze was christened.

Around 1665 John Michael Wright (age 47). Portrait of Johanna St John Baroness St John Lydiard Tregoze (age 33).

Evelyn's Diary. 20 Dec 1684. A villainous murder was perpetrated by [her son] Mr. St. John (age 32), eldest son to [her husband] S' Walter St. John (age 62), a worthy gentleman, on a knight of quality [Sir William Estcourt], in a tavern. The offender was sentenc'd and repriev'd. So many horrid murders and duels were committed about this time as were never before heard of in England, which gave much cause of complaint and murmurings.

Note. Following the aquittal of Edward Nosworthy the jury repaired to the Globe tavern in Fleet Street. An altercation broke out between St John and Francis Stonehouse. St. John and Edmund Webb both ran Estcourt through with their swords. Both were found guilty of murder, and condemned to death. St. John's mother [Johanna St John Baroness St John Lydiard Tregoze (age 53)] obtained a pardon for him at the reported price of £16,000. St. John was expected to go abroad for some time, but publicly entered the next parliamentary election at Wootton Bassett a few weeks after the close of his case, and was duly elected to James II’s first Parliament.