Blisworth Tunnel sections lined with pre-cast concrete rings. It was also used to test out the materials that were later used on the Channel Tunnel. An unused ring is on display near the south portal. Blisworth Tunnel Blisworth Tunnel is a canal tunnel on the Grand Union Canal in Northamptonshire, England, between the villages of Stoke Bruerne at the southern end and Blisworth at the northern end. The northern end is about from the northern end of the Grand Junction Canal at Braunston, Northamptonshire and the southern end about . At 3,076 yards (2,813m) long it is the third-longest navigable canal tunnel
Blisworth Tunnel backs pushing the boats with their feet (legging). From 1871 steam tugs were used to pull boats through, and extra ventilation shafts were installed. Boaters wishing to avoid the extra cost involved in using the tugs could still leg their boats through, but by the 1930s motor boats (towing a butty boat) were common so the practice would have been unusual especially by the time the film Painted Boats was filmed there in 1944. Due to changes in the shape of the tunnel over time, the tunnel became unnavigable. There was major rebuilding of the tunnel in the 1980s, with