William Fiennes was born in 1582. A close friend of George Villiers, Duke of Buckingham, he was granted the tile, Viscount Say and Sele.
On the outbreak of the Civil War Fiennes supported the Parliamentary army. His son, Nathaniel Fiennes, fought against the royalist forces but was disgraced in 1643 when he surrendered Bristol to Prince Rupert.
Fiennes sat in the Westminster Assembly which decided on the future of the Church. He also formulated the peace terms offered to Charles I in 1647. He retired from public life after the execution of the king.
Fiennes returned to power on the Restoration when he was made Lord Privy Seal. William Fiennes, Viscount Say and Sele, died in 1662.