The second son of a cadet branch of the extensive St. John family, this Member originally intended to enter the legal profession; but in 1584 his hot temper involved him in a fatal duel, and he was obliged to flee the country.
St. John remained in close touch with Mountjoy, created 1st earl of Devonshire in the new reign, consulting Sir Robert Cotton* on his behalf about the arrangement of Mountjoy’s library at Wanstead, for instance.
St. John’s other interests in the Commons included the Union with Scotland, on which he was appointed to a conference with the Lords on 14 April. Four days later he urged a further meeting, pointing out that the Scottish Parliament had already consented to the Union, and was among those chosen to marshal objections to adopting the style ‘Great Britain’ (18 April).
Appointed master of the Irish Ordnance on 12 Dec. 1605, doubtless at Devonshire’s request, St. John does not seem to have taken up his post for some four months, maintaining a high level of parliamentary activity for most of the second session.
The marriage of St. John’s niece to Sir Edward Villiers* brought him into the Buckingham circle, and helped him to procure, in 1616, the post of lord deputy of Ireland, to the surprise of many at Court.
