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
Edward Seymour, 16th Duke of Somerset Depot, with the temporary rank of lieutenant-colonel (ordnance officer, 2nd class) from 4 January 1900. He eventually became Inspector of Army Ordnance Services, and retired from the army in 1918. Seymour established his claim to the dukedom in 1925, the 15th Duke of Somerset having died without issue in 1923. He was the great-great-grandson of the Very Reverend Lord Francis Seymour, fourth and youngest son of the 8th Duke. On 28 July 1881, Seymour married Rowena Wall, a daughter of George Wall, of Colombo, Ceylon. Together, they had one son: Evelyn Seymour, 17th Duke of Somerset, born on 1 May