April 1460 found Jean in service with Henry Holland, Duke of Exeter and Admiral of England. Then in June he was in London when the City opened its gates to Richard Neville, the Earl of Warwick, and the Yorkists who were fighting to remove the Lancastrian Henry VI as King. Jean de Foix sought to hold the Tower of London with the Lords de Vescy, De La Warr, Francis Lovell and the Duchess of Exeter (she was sister to the future Kings Edward and Richard, and to Elizabeth, John de la Pole’s wife to be). As a result they missed the actual battle of Northampton, and the Yorkist victory. Although they held out in the Tower for some days, they had eventually to yield.
Although others were executed or escaped, De La Warr and Jean de Foix accepted the change to Yorkist rule. In August Jean agreed to serve under Richard Neville in Calais, and (according to Scofield) was so thoroughly liked and trusted by his former enemies that the officers of the Exchequer were directed to honour a promise Henry VI had made to him, that he should have a hundred marks towards his outstanding ransom in France. Also a license was granted on 7.12.1460 for Jean de Foix to export 2000 sacks of wool from England free of duty.
It is not clear whether Jean resigned the Garter, but according to Dr. J.Doran (‘The Knights and Their Days’ (1856)) when Edward IV ‘came into power he gave the Garter to the most useful men of the York party, beheading a few Lancastrian Knights to make way for them. At the chapter held for the purpose of electing these Yorkist aspirants, honest Jean de Foix, Earl of Kendal, declined to vote at all. He alleged that he was unable to discern whether the candidates were ‘without reproach’ or not, and he left the decision to clear-sighted people. He thus avoided a disagreeable act.’
At this point the reality that England had finished her continental adventure must have been clear. Jean de Foix in turn must have decided that he needed to return to what was now a French Gascony and consolidate his family and recover his estates. In March 1461 the new King Louis XI visited Bordeaux and, no doubt recognising the benefits of achieving their support, granted to the city and its burgesses all the rights that had existed before the French conquest. Given that trade with England had been at a standstill and substantially reduced to other countries up until that point, this must have been an easy win for Louis!