This four storey tower by the north corner of the North wing was built in 1851. In 2001, a lift was installed for those not able to use the back staircase.
The Military Room is on the ground floor and the Towneley Room on the first floor. On the second floor is a store room for oil paintings, named the Top Oil Store to distinguish it from the Large Oil Store on the first floor of the North wing. On the top floor are stores for the Natural History collections.