Rach and I were heading back from looking at a boat nr Wolvercoat when we decided to take a pit stop and came across Coate's Portal of the Sapperton Tunnel. Construction began in late 1783 and was completed in 1789, significant restoration works were carried out in 1777.
The feasibility of the restoration of the tunel has been verified despite significant damage occuring inside over the past century. At present however the canal is in poor order and the restoration works of the 70's are showing signs of age. It is a nice spot though. Hopefully one day the Thames and Severn canal will be back in working order.
There's a good article on the tunnel here;