Hamilton was known as an unscrupulous schemer and supporter of Mary, Queen of Scots (1542-87), who plotted for foreign intervention in her favour. He helped her escape from Loch Leven Castle in 1568. Having been appointed Commendator of Paisley Abbey at a young age, he fell heir to the extensive land-holdings of the abbey following the Reformation. These were erected into a Temporal Lordship and Hamilton was created the 1st Baron Paisley in 1587. In 1574, he married Margaret Seton at Niddry Castle (West Lothian) and their son became the 1st Earl of Abercorn.