When Matthew , 4th Earl of Lennox , died in 1571 , his heir was his grandson King James VI , as his eldest son Lord Darnley had died in 1567 .
The title merged in the Crown .
When Matthew , 4th Earl of Lennox , died in 1571 , his heir was his grandson King James VI , as his eldest son Lord Darnley had died in 1567 , so the title merged in the Crown .