Thrumster Mains Broch has had a long history of investigation. It was subject to a very early archaeological excavation in the early 1800s. A summer house was put into the west side of the wall around the same time.
In 2011 AOC archaeology in conjuction with Yarrows Heritage trust conducted a community excavation of the Broch. Originally it was thought to have been a single walled broch, however a central staircase was found and some internal cells.