The canal tunnel at Blisworth on what is now the Grand Union Canal has a long history. Work initially started shortly after approval for the (then) Grand Junction Canal was granted in 1793. This initial excavation was abandoned three years later after collapses in quicksand which claimed the lives of 14 men; it seems the chosen course intercepted an underground stream or water course.
It was suggested by William Jessop - the main civil engineer on the project - that a flight of 29 locks could be built to remove the need for a tunnel but the resident engineer James Barnes maintained that a tunnel was essential. Work started again in 1802 - two years after the rest of the canal had been completed. A revised course was chosen to avoid the bad ground of the initial attempt.
Until the tunnel’s final completion in 1805, a double-tracked tramway was built over Blisworth Hill and the contents of the barges were laboriously unloaded and reloaded and drawn by horse over the summit. Once opened, there being no towpath within, boats had to be laboriously legged through the tunnel. An innovative steam hauled continuous wire rope was installed around 1869. This in turn was replaced by steam tugs which provided haulage between 1871 and 1936.
Reduced traffic and lack of maintenance led to the closure of the tunnel in the 1970s but a major project led to its re-opening in 1984. The central section of the tunnel was reinforced with cast concrete segments, some aspects of the work being a pilot for the tunnel linings used for the channel tunnel. An unused segment liner is on display at the southern portal of the tunnel.
Today, at 3,076 yards (2,813 metres), the tunnel is the third longest canal tunnel in the UK (after Standedge and Dudley). As the tunnel is 15 feet wide it is the longest in the world where craft (narrowboats up to 7 feet wide) can pass at all points within. The village of Stoke Bruerne, a short distance from the south portal of the tunnel, is at the top of a flight of locks and has a canal museum run by the Canal and River Trust which includes some exhibits relating to the tunnel. A couple of local operators offer trips through the tunnel from Stoke Bruerne during summer months or by arrangement.