We may be reasonably certain that the John Warwick who served on a royal commission of inquiry set up in 1380 to investigate the problem of counterfeiting in Northamptonshire and other parts of England was later returned to Parliament as a shire knight, although nothing more can be said about him at this time. Indeed, save for this early connexion with the county of Northamptonshire, which he was later to represent in the House of Commons, his background and circumstances remain thoroughly obscure. In August 1384 he acted as a mainpernor for a Wellingborough man charged with leaving his employer’s service before the appointed time. Otherwise, it is not until May 1390 that his career can be followed in any detail. He then joined with a neighbour in taking a three-year lease of the manor of Yardley Hastings (Northamptonshire) at an annual rate of £85 payable at the Exchequer. Warwick had clearly begun to acquire an impressive circle of friends, for in December 1392 he and Sir Nicholas Styuecle were involved in certain unspecified financial transactions with the prior of Ely, Sir James Roos and Sir Philip Tilney, to whom they offered securities worth £400. Although he was not formally retained by Richard II until April 1393, when he received a promise of 20 marks a year for life, Warwick must already have had some influence at Court to secure the post of forester of the royal forest of Savernake in the previous February.
Even so, by the time of the Lancastrian usurpation, in the early autumn of 1399, Warwick had made such an effective and convincing change of allegiance that he was not only retained by the newly crowned Henry IV as an esquire of the body, but also appointed to serve another period in office as sheriff. His appearance, in December 1397, among the persons standing surety at the Exchequer for Jancio Dartasso, a prominent supporter of the house of Lancaster, may possibly denote some earlier shift in Warwick’s political sympathies, although he was no doubt driven more by force of circumstances than personal commitment to throw in his lot with Richard’s enemies. He nevertheless proved a loyal and efficient crown servant; and even though his second term as sheriff of Northamptonshire was marred by the escape from his custody of a group of felons Henry IV saw fit to offer him a full pardon for his negligence. The county electors may well have chosen Warwick to represent them in the two Parliaments of 1401 and 1406 because of his position at Court, but we must not forget that he was a leading local figure in his own right. It was certainly for this reason, and not because of his other connexions, that the Commons of 1406 nominated him to act as one of six arbitrators in an already protracted dispute over the ownership of the Northamptonshire manor of Hinton-by-Brackley, which had come before them during the course of the session. In actual fact the quarrel was eventually settled by two umpires after a further delay of almost four years, but Warwick himself seems to have been conscientious enough in discharging his responsibilities.
Another mark of royal favour came Warwick’s way in June 1405, by which date a marriage had been arranged between his daughter, Joan, and William Park. As compensation for persistent arrearages in the payment of his annuity, Henry IV gave his esquire £40 to mark the event. He still found it difficult to collect his pension, however, and as late as 1419 orders were being issued for the settlement of his claims upon the Exchequer.
Rather less is known about Warwick’s personal affairs, which are not well documented. He twice offered securities at the Exchequer on behalf of his friend, Sir William Arundel, to whose use he held the manor of Bingham in Nottinghamshire. He was also on close terms with his parliamentary colleague, John Cope, for whom he likewise acted as a trustee; and from time to time his name appears among the witnesses or parties to local property transactions. In 1406 he joined with Sir John Trussell and Thomas Mulsho to stand bail at the Northampton assizes for the defendant in a case of assault, but little other evidence has survived of his involvement in county society.
Warwick is last mentioned on 12 Feb. 1419, when instructions were given by Henry V for the payment of his annuity. Given that he had for some years already been described as elderly, his death probably occurred soon afterwards.
