Although it is sometimes difficult to distinguish John Croft from his father and namesake, we can be reasonably sure that the latter died in about 1371, holding the estates in Dalton which had belonged to his family from the reign of Henry II if not before. We know that by 1396 John was also in possession of the manor of Leghton; the advowson of Claughton church and land in Yealand Conyers and Over Kellet in Lancashire, as well as other property across the border in Farleton, Westmorland. His income as a rentier was later estimated at about £40 p.a., although he may well have been far richer. His inheritance in Dalton alone was evidently quite extensive, as in 1372 he obtained a royal licence to impark 500 acres of arable and woodland there. The problem of keeping poachers out of his free warren exercised him considerably at this time, and he was involved in litigation against several people for trespass. Paradoxically, John himself had earlier, in 1365, stood charged of stealing deer, fish and timber from the widowed Joan Coupland; and he had been summoned before two commissions of oyer and terminer as a result — albeit with no detrimental effect upon his career.
In August 1368 either John or his father witnessed a deed for the prior of Lancaster. It was almost certainly the younger man who, three years later, began to serve as a royal tax collector in Lancashire; and from then on he appeared regularly as a crown commissioner. He married at some point before 1377, when he and his wife sued out various writs in the chancery of the duchy of Lancaster. His relations with John of Gaunt, the duke, grew steadily closer, for as one of his leading feudal tenants it was natural that Croft should be called upon to hold some local office. The date of his appointment as verderer of the forests of Quernmore and Wyresdale is not recorded, but in 1387 he was replaced because of the demands made upon his time by the three duchy stewardships which he had already exercised for four years. Other urgent business preoccupied him during this period, and in January 1385, not long after he had been knighted, he prepared to leave England for Portugal, probably on a diplomatic mission concerning Gaunt’s claim to the throne of Castile.
In point of fact, Sir John’s attachment to Richard II was by no means so strong as to jeopardize his position once Henry of Bolingbroke had seized the throne. Mindful not only of Sir John’s loyal service to his father, Gaunt, but also of his wide experience as an administrator, the newly-crowned Henry IV confirmed him in the first of his two annuities; and at some point before October 1402 he made him captain of the castle of Marck in the march of Calais. While in office, Sir John spent several months at Calais as an ambassador for the negotiation of a truce with Flanders, receiving 20 marks by way of both reward and expenses. He was, none the less, obliged to relinquish his post in February 1405, ostensibly because old age and ill health prevented him from remaining overseas. His captaincy was marked by a territorial dispute with his predecessor, John Lancaster II, which had still to be settled three years later. Notwithstanding his reputed illness, Sir John was well enough to raise troops for Henry IV during the turbulent summer of 1405, and also to perform another round of jury service in the following year. Nor did age prevent him from attending the Lancashire elections held some years later to the Parliaments of 1413 (May) and 1419.
The precise date of Sir John’s death is unclear, being given in one source as 31 Dec. 1419, and in another as the following July. He was survived by his second wife, Joan, and by his eldest son, who inherited the bulk of his estates and later received an annuity of £10 from the Crown.