He appears as "Lord of Badenoch" as early as 1229, after the defeat of the Meic Uilleim by his father.
Like his father, Walter was given the hand of an heiress, Isabella, Countess of Menteith.
[1] Walter appears to have had a son named Henry who witnessed a charter, dated to 1250, of Maol Domhnaich, Mormaer of Lennox.
[citation needed] Walter was one of the leading political figures in the Kingdom of Scotland, especially during the minority of King Alexander III, when, along with Alan Durward, he essentially ran the country.
He is remembered primarily in the proverbial expression Walter of Guiyock's curse, encountered in Sir Walter Scott's Rob Roy, under the English and Lowland form of his name, Walter Cuming, where it appears in chapter 29: ... and that they shuld dee the death of Walter Cuming of Guiyock, wha hadna as muckle o'him left thegither as would supper a messan-dog...[2]The origin of this is related in Sir Walter Scott's note at that page: A great feudal oppressor, who, riding on some cruel purpose through the forest of Guiyock, was thrown from his horse, and his foot being caught in the stirrup, was dragged along by the frightened animal till he was torn to pieces.