Career
He is remembered notably for having secured the styling of Most Faithful Majesty for the Portuguese monarchy, in 1748, and for compiling what is now known as the Weale Album (Portuguese: Álbum Weale), an extensive catalog of artistic commissions by John V for Lisbon from Rome. The exact details of his origins are unclear, it is known that Pereira de Sampaio was born in Lagos, in the Algarve, as a bastard of a minor Fidalgo of Portuguese nobility. His position as governor, his personal reports on Pope Benedict XIV to King John V, and his close relationship with João Baptista Carbone, personal secretary of the Portuguese king, were all deciding factors in his nomination as ambassador to the papal court.
While ambassador, Pereira de Sampaio cataloged the numerous artistic commissions made by King John V in Rome, including artwork destined for Ribeira Palace and the famed Chapel of Saint John the Baptist, destined for the Igreja de São Roque, in what is now known as the Weale Album.
Pereira de Sampaio died in February of 1750, in Civitavecchia, of an asthma attack, while preparing for an expedition back to Lisbon with works of art destined for the Patriarchal Basilica in Lisbon. He is buried in Sant"Antonio dei Portoghesi with a funerary monument dedicated to him designed by Filippo Della Valle.