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
Whilton Locks who were brought in to advise. Low level headings were cut to drain the main workings of water, and the tunnel opened on 25 March 1805, the last part of the canal to be completed. The Grand Junction Canal became part of the Grand Union Canal in 1929, following amalgamation with the Regents Canal, the Warwick and Birmingham Canal and the Warwich and Napton Canal. Below the bottom lock was a long level pound stretching to beyond Blisworth Tunnel. The seven locks raised the level of the canal by to a fairly short summit pound, which passed through Braunston Tunnel