William Master was born in 1600 in Gloucestershire, England, the son of George Master and Bridget Cornwall, daughter and heiress of John Cornwall, Esq.
[1] In 1622, he was knighted by King James I, and in 1623, elected to represent Cirencester in Parliament.
He served as High Sheriff of Gloucestershire in 1627 following his appointment to the position by King Charles I.
[2][3] Initially Master was favourable to Parliament at the outbreak of the English Civil War, however, following the Royalist invasion of his town, Master signed over contributions to the Royal Army after Prince Rupert and Prince Maurice were quartered in his home, and he became a staunch Royalist.
[2][3] King Charles I would also spend time in Master's home, once in August 1642 en route from Oxford to Bristol and again in 1644 en route from Oxford to Bath.