William Seymour, 2nd Duke of Somerset was the great-grandson of Edward Seymour, 1st Duke of Somerset (c.1500-1552), the uncle of King Edward VI and Lord Protector of England. Seymour made a secret marriage at Greenwich on 22 June 1610 to Arbella Stuart (d.1615), daughter of Charles Stuart, 1st Earl of Lennox and Elizabeth Cavendish. Arbella was thirteen years his senior, and King James I disapproved of the marriage as the union of two potential Tudor pretenders to the throne, who were respectively fourth and sixth in line, could only be seen as a threat to the ruling dynasty. As a result, William was condemned to life
Duke of Somerset together with the barony of Seymour, devolved on his distant cousin. Sir Edward Seymour, 6th baronet of Berry Pomeroy (1694–1757) became the 8th Duke of Somerset in 1750. The 1st baronet was (Sir) Edward Seymour (1556–1613), son of Edward Seymour (1527/1535–1593) who was the 1st Duke's eldest son and of Catherine Seymour (née Fillol). He was seventh generation offspring of the 1st Duke. The 4th Baronet had been speaker of the House of Commons during the reign of Charles II and he moved the family home from Berry Pomeroy Castle in Devon to Bradley House in Maiden Bradley. Upon this