Basin was present at the Council which began at Ferrara, but which was transferred to Florence by decree of Pope Eugene IV on 10 January 1439. During the Council he made the acquaintance of the humanist Poggio Bracciolini, which blossomed into a friendship of twenty years. Both worked on the council's business under the direction of Cardinal Cesarini, the president of the council. On 21 March 1439 Basin was named a Canon of the Cathedral Chapter of Lisieux. In July 1439 he was appointed to an embassy to Hungary, led by Cardinal Cesarini. The embassy was made very difficult when Albert of Austria, King of Hungary, died on 14 October 1439, and a struggle for election to the throne began between supporters of Władysław III of Poland and Queen Elisabeth of Luxembourg. The embassy returned to Florence on 26 March 1440. Basin was soon made Canon and prebendary of the Cathedral Chapter of Rouen by Pope Eugene as his reward for service on the legation. His senior colleague on the embassy, Giovanni Tagliacozzo, was made a cardinal. In 1440 Basin was ordained a subdeacon, but he did not remain long in Italy. On 23 May 1441 he took his stall in the Cathedral Chapter of Rouen. In November 1441 the English Royal Council named him professor of canon law in the new University of Caen. On 1 October 1442 he was elected Rector of the University of Caen. He also became vicar-general for the bishop of Bayeux, Zeno Castiglione, who was a member of the English Royal Council. Basin was one of the negotiators appointed by King Charles VII on 10 June 1445 to negotiate a marriage between one of his daughters and Edward, Duke of York.