Gunthorpe returned to England in 1465 and became intimately integrated into the religious, diplomatic, financial, and political life of the court and government of Edward IV. Gunthorpe's involvement in Anglo-Castilian diplomacy concluded in 1470 when he was one of the ambassadors commissioned on 14 March by King Edward IV to embark upon an ultimately fruitless effort to persuade Enrique IV against the repudiation of the treaty between their kingdoms. Gunthorpe was in the royal household as a king's chaplain by the summer of 1466.
