He was Master of the Rolls in Ireland between 1696 and 1731 and also held political office as Chancellor of the Duchy of Lancaster from 1710 to 1714 and as First Lord of Trade from 1714 to 1715.
He was born on an unknown date between John's 1663 birth and 23 March 1672 which would have made William a septuagenarian by the time of his death in 1741.
In 1696 Berkeley was appointed Master of the Rolls in Ireland and sworn of the Irish Privy Council.
In 1710 he was admitted to the English Privy Council and appointed Chancellor of the Duchy of Lancaster.
Lord Berkeley of Stratton remained a widower until his death at Bruton, Somerset, in March 1741.