John Duke of Essex served at Crécy and Calais, and in 1347 was with many others granted a pardon for his service, provided he continued to provide military service in France, apparently indefinitely. Edward III issued these pardons from Calais:

Pardon, for good service in the war of France, to John son of William Whyssh of Donecastre, co. York, of the king's suit against him for any homicides, felonies, robberies and trespasses in England before 4 September last, and of any consequent outlawries; on condition that so long as the king be on this side the seas he do not withdraw from his service without licence. By K. and testimony of William atta Wode.

There is no indication in the published record of what specific offense required pardon. This John Duke seems to have established a home at Widdington, Essex. However, William Trussebut, who testified to his service, was of the retinue of William de Bohun, Earl of Northampton.

In 1367 John Duk the younger [implying the existence of an elder, probably the same individual who served at Crécy] and his heirs were granted free warren of their demesne lands of Wedyton, Essex, by Edward III. Wedyton (Widdington) is in northwestern Essex. Prior's Hall and Prior's Wood appear to be the portions of the property held by the Priory of Tackle(y) in Essex, in turn held by the French Prior of St. Valery as a consequence of a donation by William I.

In 1380 and in 1384 John Duke of Essex is mentioned in connection with Tackle(y) grants. In 1390, John Duke was commissioned with others to convene a jury of Middlesex and Essex touching waste and dilapidation at the alien priory of Takley, in the king's hand on account of the war with France.

John Duke was a commissioner of array for Essex, responsible for conscripting troops for the king's military service, in 1384. His companions in this post were very distinguished, including the earls of both Oxfordshire and Buckinghamshire (who do not appear on the lists for their own counties) and a member of the Bouchier family, later earls of Essex.

In 1398, John Duke was among those assigned by Richard II to provide to the Exchequer £2000 from the county of Essex.

In 1399, John Duke and all others present in earlier royal commissions in Essex are absent. This may relate to the radical change in royal government at this time. In 1399 Richard II was deposed, and murdered. Henry IV took his place, establishing the Lancastrian dynasty on the throne of England for many decades.

Richard II exempted John Duke of Wydyton from unwilling appointment to a wide range of positions, apparently in recognition of prior service. In 1400, this was confirmed by Henry IV:

Exemption for life of John Duc of Wydyton from being put on assizes, juries, inquisitions or recognitions and from being made mayor, sheriff, escheator, coroner, justice of the peace or of labourers, collector of tenths, fifteenths or subsidies, taxer, trier, assessor, captain or governor of men at arms, hobelers or archers or other bailiff or minister of the king against his will.

This confirmed an earlier statement to the same effect by Richard II.

In 1399, Guy Duke went on Richard II's Irish campaign. In 1402, Guy Duke of Essex gave recognisance for 100s. to Robert Ramsey. In 1403 Guy Duke of Essex gave recognisance for 350 marks to Nicholas Wolbergh, citizen and fishmonger of London. This is doubtless the same Guy Duke who served with Bouchier at the Battle of Agincourt in 1415.

John Duke reappears in a 1405 reference:

John Lerlyngton and William Folborne to John Duke of Weditone. Recognisance for 56s. 8 d. payable a month after Easter next, to be levied etc. in the county of [left blank]
. The said John and William to John Duke of Weditone. (like) recognisance for 56s. 8d payable a month after Michaelmas next. [county again left blank]

It is unfortunate that this reference omits an intended reference to the county, since there are quite a few locations named "Weditone" in late medieval England. However, the Essex location is the only one of these known to have been the residence of a Duke family, and specifically a John Duke, at this time.

After 1405 there are no more references to the Duke family at Widdington.