Physician Balthasar Guersie was born in Italy (place and date are not known). Having been surgeon to Queen Catharine of Aragon around 1515, he was naturalised in March 1521/2. About 1530 took the degree of Bachelor of Medicine at Cambridge University. He was also surgeon to Henry VIII. In 1543 he was engaged in collecting accusations against Archbishop Cranmer. He was admitted a Fellow of the College of Physicians in December 1556. He died in January 1557.