He was apparently instructed in a dream to found the castle on the spot where he first heard a blackbird sing, whilst making his way down the strath of the Tay.
On 3 August 1564 Mary, Queen of Scots wrote from Glen Tilt to Colin Campbell of Glenorchy, asking him to demolish a house of strength on an island in Loch Rannoch.
On 7 April 1570, after securing the consent of the Regent Morton, Colin personally beheaded Gregor at Balloch, in the presence of the Earl of Atholl, the Justice Clerk.
Gregor's wife, Marion Campbell, who also witnessed her husband's execution, wrote a bitter lament about the affair, called 'Griogal Cridhe'.
In the Black Book of Taymouth, Sir Colin was described as a great 'justiciar' of his time, who sustained the deadly feud with the Gregor clan and executed many notable lymmars (rogues).