From medieval times Boroughbridge was part of the parish of Aldborough in the West Riding of Yorkshire. In 1553 it became a parliamentary borough, electing two Members of Parliament to the unreformed House of Commons. It had a burgage franchise, meaning that the right to vote was tied to ownership of certain of property in the borough and had less than 100 qualified voters by the time it was abolished in the Reform Act of 1832: It was a pocket borough under the control of the Dukes of Newcastle. Augustus FitzRoy, who was Prime Minister as the 3rd Duke of Grafton, was elected MP for Boroughbridge in 1756; but never sat for the borough as he preferred to represent Bury St Edmunds where he had also been elected.