Malcolm was given the barony of Kirkintilloch[1] forfeited from the Comyns by King Robert I of Scotland during the First War of Scottish Independence and received other lands in Lennox and Wigtownshire.
Malcolm was on the defeated Bruce side at the Battle of Halidon Hill in July 1333, but managed to escape, and fled back to Dumbarton.
He was partly responsible for sending the boy king, Robert's son David II from Dumbarton to exile in France.
On 17 October 1346, Malcolm was captured at the Battle of Neville's Cross and imprisoned by Robert Bertram, sheriff of Northumberland, but escaped the following year to Scotland.
Malcolm's successor to the earldom of Wigtown, his grandson Thomas, had grave financial problems and was stripped of the rights of regality given to his grandfather.