Restored by Cotswold Canals Trust. Formerly known as Upper Nassfield Lock, it is the top lock of the five in the Eastington flight, built in 1777, and has a rise of 7 feet 5 inches.
The chamber is mainly lined in brick, with stone capping and stone quoins to the gate recesses. The mouth and the tail sections are lined mainly in brick as well. There are paired vertical sluices on either side of the approach, or mouth, of the lock above the top gates.