Walter married, in 1315, Marjorie, only daughter of Robert I of Scotland by his first wife Isabella of Mar. The Lordship of Largs, taken from John Balliol, was given to Walter by Robert the Bruce, who also gave him the Farme Castle lands in Rutherglen as well as other lands and the barony of Bathgate, Linlithgowshire. Walter and Marjorie had one son: