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
Grand Junction Canal canal from the Thames reached Two Waters near Hemel Hempstead in 1798, Bulbourne at the north end of the Tring summit in 1799, and Stoke Bruerne at the south end of Blisworth Tunnel the following year. Thus, with the exception of Blisworth Tunnel, the main line was fully open in 1800. To allow goods to cross the gap, a road was built in 1800 over the top of Blisworth hill and, later, upon the recommendation of committee member Joseph Wilkes, Benjamin Outram was contracted to build a tramway over the hill. James Barnes proposed that work begin again on the