John St John, 2nd Viscount St John

In 1721 his father invested £4,000 to acquire the reversion of a customs sinecure worth £1,200 a year for the lives of his two younger sons, John and Holles.

St John married Anne Furnese, daughter of Sir Robert Furnese, 2nd Baronet of Waldershare, Kent on 17 April 1729,[1] At the 1727 British general election after coming of age, St John was returned as Member of Parliament for Wootton Bassett on the family interest.

[1] St John was appointed Comptroller of customs in London in April 1740 holding the post for life.

On his father's death on 8 April 1742, he succeeded not only to the title under special remainder as 2nd Viscount St. John but to Lydiard Park.

[1] St. John died abroad in November 1748, leaving three sons and three daughters.