On the 30th June 1597, he was ordained by the Privy Council to find caution to the extent of 1000 merks, and on 15th March 1610, he was appointed a Commissioner of Peace for Shetland. He appeared as a witness at Edinburgh along with others against Earl Patrick in 1610, and “await there upon their complaints, and dare not pass home from fear of the Earl”, as he may be learned from the Privy Council Register.
In 1611 there seems to have been a feud between this family and the Sinclairs of Houss, and a complaint having been made by the Lord Advocate to the Privy Council, the parties were summoned to Scalloway. In obedience to this summons William Bruce and Robert, his son, proceeded to Scalloway, where they were attacked by Laurence and James Sinclair, sons of Arthur Sinclair of Houss, and their retainers, to the number of forty, who so ill-treated them that they were left for dead. On 28th January 1612, it is reported that the parties had given their great Oath that they would keep the peace inviolate, and for a further manifestation of their sincerity they had “choppit handis togedder”. William Bruce returned to Fifeshire, his native country , where he died about 1630, and was buried at Crail, where his monument is still to be seen.
By his wife Marjorie, daughter of John Stewart, Prior of Coldingham, (a natural son of James V and Elizabeth, daughter of Sir John Carmichael of Crawford) and widow of William Sinclair of Underhoull, she died 25th November 1607, he had issue:
By his second wife, Isabella, daughter of Sir James Spence of Wormiston, he had a son Andrew, from whom the family of Pittarthie in Fifeshire was descended.