In 1347, possibly in September, Islip was appointed keeper of the Privy Seal. Previously he had held the seal of
Lionel of Antwerp, the King's second son, who was the regent in England. He enjoyed the trust and confidence of
Edward III, who relied on him in political and diplomatic as well as Church affairs, and gave him extensive powers during his absence in France. Though loyal to the King he did not hesitate to oppose him where the affairs of the Church were concerned, and later addressed a famous remonstrance, the
Speculum Regis Edwardi, refusing the King's demand for a tenth of ecclesiastical income for six years. He vacated the office between 21 February and 1 May 1350. ==Archbishop of Canterbury==