William Keith, 7th Earl Marishcal was appointed a Privy Councillor in 1641. An active Covenanter, he remained loyal to the cause, refusing to give up fugitives to the Marquess of Montrose who defected in support of King Charles I as the English Civil War developed. He was beseiged at Dunnottar Castle in 1645 and later imprisoned in the Tower of London. Following the Restoration, he was appointed Keeper of the Privy Seal of Scotland.