Pietro Peregrosso was Treasurer of the Church of Laon and of the Church of Cambrai, and he was a Canon of Chambéry and Canon of the Cathedral of Paris. All of these appointments were sources of income, not offices which required one to care for souls of Christians. He was Vice-Chancellor of the Holy Roman Church under Popes Innocent V, Adrian V, John XXI, Nicholas III, Martin IV, Honorius IV and Nicholas IV (i.e. from 1276 to 1288). This office made him the effective head of the papal Secretariat in the
Roman Curia. In the earliest surviving papal bull which he supervised, he signs as
Magister Petrus de Mediolano. He was commended by King
Edward I of England for being especially attentive to expediting the King's business in the Roman Curia. In 1279, as
Pope Nicholas III was preparing his bull on the regulation of the Constitution of the
Ordo Minorum (
Franciscans), he appointed an editorial committee to give the document its final form. Members of the committee were: Petrus Peregrosso, the Vice-Chancellor; Comes Giusiano de Casate, the Auditor of the Apostolic Palace; the Curial Advocate Angelo; and
Benedetto Caetani, the protonotary. The results of their work was embodied in the
Liber Sextus of the Code of Canon Law. ==Cardinalate==