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 opened on 21 May 1991. The by-pass runs to the west of the two villages, now following a newly created route from Tiffield. The road joins the M1 London to Yorkshire motorway at a new junction created at that time, 15A, at West Hunsbury, Northampton. From Northampton to Blisworth the by-pass closely follows the trackbed of the Blisworth to Northampton railway, long since closed. The new road makes a slight detour near the Northampton arm of the canal at the 'staircase' of locks near Rothersthorpe. The road's construction followed many years of long campaigns in the two villages. The London