Grand Junction Canal Nene at Northampton, to the turnpike road at Old Stratford (north-west of the modern Milton Keynes), and to Watford in Hertfordshire: those to Daventry and Watford were not built. The branch to Old Stratford was amended before it was built (see below). The branch to Northampton was delayed as the plans of the Leicestershire and Northamptonshire Union Canal to reach Northampton and thus join with the Grand Junction came to nothing. The link to Northampton was made by a tramroad transferred from Blisworth Tunnel, with the 5-mile (8-kilometre) canal from Gayton being opened in 1815. The link to Leicester was
Sapperton Canal Tunnel workmanship, as it had to be closed for ten weeks after only a year, while repairs were carried out. It was superseded as the longest canal tunnel in England in 1811 by the Huddersfield Narrow Canal's Standedge Tunnel, which was long when built, later extended to to accommodate the adjacent railway tunnel, and remains the highest, longest and deepest canal tunnel in Britain - though, unlike Sapperton, Standedge can only accommodate . Strood Tunnel on the Thames and Medway Canal was also longer at when it opened in 1824, but was cut in two in 1830 by opening out a