The Rochfords had long been one of the leading families in Boston, and by the mid 14h century their influence made itself felt throughout Lincolnshire. John’s father, Sir Saier, served as both sheriff and escheator of the county, and was also returned as a shire knight to the Parliament of 1343. His uncle, Sir John, distinguished himself in the French wars, fighting under the banner of John of Gaunt, whom he followed loyally for years. He too represented Lincolnshire in the House of Commons, and became closely involved in the work of local government from the late 1370s onwards. That the young John Rochford would follow the example of these two men seemed a foregone conclusion, and he must still have been quite young when, in November 1379, he was appointed to his first royal commission, which involved an inquiry into disorder at Boston.
By the date of his first return to Parliament in 1390, Rochford had already been sitting on the bench in the parts of Holland for almost eight years, and, moreover, appears to have been retained at a fee of 40s. by the dean and chapter of Lincoln cathedral. He was once again in office as alderman of the Corpus Christi guild when, in May 1392, he, his friends Bell and Tilney, and others of the brethren obtained a royal licence to endow it with additional property worth over £5 a year. Not content with this single work of piety, the three men were also the moving spirits behind the foundation of another guild in Boston, which was to be dedicated to God and the Virgin and be supported out of a landed income of £10 p.a. The letters patent authorizing this endowment were obtained at the supplication of Queen Anne, since most of those involved were her own tenants. Besides appearing together from time to time as feoffees, Tilney and Rochford were both appointed to the royal commission set up in March 1393 to deal with the civic disputes which were then disrupting the government of Lincoln. In the event, this delicate undertaking was considered unsuitable for so formal a body, but Rochford’s inclusion among the original commissioners clearly reflects his growing influence. Further evidence of this is to be found in his appearance, in 1397, as a trustee of Sir Simon Felbrigg KG, standard-bearer to Richard II, and the award to him in 1398 and 1399 of papal indults for the use of a portable altar and for plenary remission of sins at the hour of death.
Understandably enough, in view of his strong connexions with the new regime, the electors of Lincolnshire chose Rochford to represent them in what was to become Henry IV’s first Parliament. He continued to enjoy the monarch’s good will, retaining his post on the duchy of Lancaster estates, and, one year later, embarking upon his second term as sheriff. During this period he was summoned to attend a great council at Westminster, and also obtained the post of constable of Wisbech from John Fordham, bishop of Ely, at a fee of 20 marks p.a. This appointment, which was clearly no sinecure, enabled him to extend his authority into Cambridgeshire, and no doubt helps to account for his return as one of the county Members to the Gloucester Parliament of 1407. Meanwhile, in March 1403, he and his brother were rewarded with the keepership of the estates of Sir James Roos’s younger son, Robert, who was then a royal ward. The raising of troops to fight against the rebellious Welsh and King Henry’s other enemies took up a good deal of Rochford’s time during the turbulent early years of the century; and he himself may have taken up arms, albeit briefly, for purposes of national defence. He certainly became involved in a personal confrontation during this period, for in the spring of 1406 he was bound over in sums of £100 to do no harm to one Robert Kerville, whom he appears to have threatened or assaulted. His mainpernors on this occasion included Sir Walter Tailboys, John Skipwith and Sir John Copledyke, a Lincolnshire landowner to whom he was apparently related.
Given his active career as an administrator, man of affairs and possibly soldier, it is all the more surprising to discover that Rochford was something of a scholar noted for his interest in historical and literary work. Although subsequent research has shown that certain texts previously attributed to his pen were merely glossed or extended by him, his achievement was none the less considerable. Whether or not he studied as a young man in Italy and France (as Pits believed) we shall never know, but towards the end of his life, at least, he compiled digests of and indexes to various well-known chronicles; and he may even have translated works for English readers. In 1406, for example, he completed his Notabilia Extracta per Johannem de Rochefort Militem de Viginti et uno Libris Flavii Josephi Antiquitatis Judaice; a Tabula super Flores Storiarum (an index of the Flores Historiarum of Matthew of Westminster) followed; and in 1410 he produced Extractum Chronicarum Cestrensis Ecclesiae.