 In 1661 Argyll too was executed, and Mugdock was returned to the Grahams, who restored the castle over a two-year period, building a mansion within the old castle walls.In 1682 the Grahams bought Buchanan Auld House near Drymen, a dwelling more fitting the title of "Marquess", though the family's official seat was kept at Mugdock Castle for a some time.A terraced walled garden, incorporating a summer house, was built to the east of the castle in the 1820s.