Duarte Brandão came from the Jewish community of Portugal. He was the bastard son of Mariana, the wife of a Jewish blacksmith. Later Portuguese genealogy records indicate that his father could have been a Fernão Rodrigues Alardo, the main alcaide of Leiria and Óbidos. These differences are perhaps attributable to the efforts of subsequent genealogists to "Christianise" his ancestral lines, however no evidence is found to conclusively support or disprove this attribution.
Life in England
Born in about 1440, to the Portuguese Jewish community, Duarte emigrated to England during the late 1450s. In order to be accepted at court, he converted to Christianity, with King Edward IV  standing as his sponsor. Upon his conversion he adopted the English name of Edward Brampton in honour of his Sponsors. Brampton was an adventurer, soldier, and ship's commander, who and fought in several engagements during the War of the Roses, including the Battle of Tewkesbury, and was eventually awarded the position of Governor of Guernsey. With the help of his wife Lady Margaret Brampton, he won favours in both the Portuguese and English royal courts and was knighted in August, 1484 by Richard III.
Following the defeat of Richard III, Brampton left England for the court of Margaret of Burgundy, where it is presumed he met Perkin Warbeck, a pretender to the throne of England, who he later employed. 
From his marriage to Lady Margaret Beaumont, he had six children: João, Jorge, Henrique, Isabel, Maria and Joana.
- Oxford Dictionary of National Biography, Rosemary Horrox, ‘Brampton, Sir Edward (c.1440–1508)’, rev. first published 2004
- Sir Edward Brampton: AN ANGLO-JEWISH ADVENTURER DURING THE WAR OF THE ROSES
- The first of the Tudors: a study of Henry VII and his reign, (Taylor & Francis, 1981) By Michael Van Cleave Alexander, page 97
- Roth, Cecil (1918–1920). "Perkin Warbeck and His Jewish Master". Transactions (Jewish Historical Society of England). 9: 143-162.