Blisworth Tunnel has no tow path inside, but is wide enough for two narrowboats to pass in opposite directions. Work began in 1793, but errors by contractor left a wiggle in the tunnel, and after three years work it collapsed due to quicksand, claiming the lives of 14 men. It was then decided to begin again with a new tunnel. By the time the rest of the Grand Junction Canal had opened between London and Braunston, Northamptonshire in 1800, apart from the crossing of the River Great Ouse, the section of canal from Blisworth to the lower end of Stoke Bruerne locks
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