He was born at Closeburn Castle, the third son of Sir Thomas Kirkpatrick, 2nd Baronet of Closeburn, and Dame Isobell Lockhart. His father died before William and his older brother Thomas (later 3rd Baronet of Closeburn) turned 18, which led to local gentleman and future Member of Parliament Charles Areskine (Erskine), Lord Tinwald overseeing the end of their formal education.
lieutenant is likely he encouraged William to read law and attend Leiden University in the Netherlands. William married Areskine"s daughter Jean Erskine, 21 years his junior, on 21 December 1746 in Edinburgh, and they had at least five children. Jean died in childbirth aged just 26 on 23 September 1752.
Once qualified in law, William held the post of Regius Professor of the Law of Nature and Nations at Edinburgh from 2 December 1734 to May 1735, replacing Areskine who had stepped aside for him.
There then followed a protracted dispute over a double return (where the returning officer declares both pairs of candidates to be elected, leaving the House of Commons to make the decision) of that bi-election, the result of which was that William did not take his seat until 13 February 1736. William died on 17 October 1777 at Shaws House, Dumfriesshire aged 72.
8th Parliament of Great Britain]
He served as Member of Parliament until 1738, at which point he became Clerk of Session at the Court of Session.
