It was constructed early in the 19th century to link the town of Tavistock to Morwellham Quay on the River Tamar, where cargo could be loaded into ships.

The canal is still in use to supply water to a hydro-electric power plant at Morwellham Quay, and forms part of the Cornwall and West Devon Mining Landscape World Heritage Site.

The canal would be suitable for tub boats, and would be built entirely on land owned by the Duke of Bedford, who approved of the project.

When cutting of it began, copper ore was discovered close to the Tavistock end, and this became the Wheal Crebor mine, which was managed as a separate project.

[8] The 2,540-yard (2.32 km) tunnel was cut through rock, was of small bore, and required Taylor to construct two types of pump, one to keep the workings drained, and the other to clean the air.

[9] The tunnel, which was driven through elvan rock and killas clay-slate, is 360 feet (110 m) below Morwell Down at its deepest point, and it was finished in 1816.

[10] At the tunnel's southern end, the canal was on the 250-foot (76 m) contour, and Taylor constructed an inclined plane to drop the level by 237 feet (72 m) to the quay at Morwellham.

Four-wheeled tipping wagons which had larger wheels at the front than at the rear were used on the twin tracks, which operated independently.

[12] The main line of the canal was formally opened on 24 June 1817; this was marked by ships on the River Tamar firing a 21-gun salute.

This was designed to attract industry to its banks, as it resulted in a flow of water along the canal, which aided the passage of boats towards the quay, and also helped to power waterwheels along the route.

This cost £8,000, and because there was a lack of water to supply locks, the difference in level was accommodated by building a counterbalanced, double track inclined plane.

[17] The branch appears to have closed around 1831, but in 1844, the owners of a new slate quarry at Mill Hill requested that the company re-open the canal or replace it with a tramway.

The canal above the Gunnislake to Tavistock road crossing was relaid as a tramway at a cost of £1,381, but the quarry was not a success, and only shipped slates between 1848 and 1850.

[18] Despite its modest length, the canal's design and execution was a remarkable achievement, owing much to the foresight and determination of John Taylor.

However, Mr T. Knight proposed a system of ropes powered by waterwheels to pull the boats through the tunnel, and the machinery was installed.

Two years later, the duke made an offer of £8 per share, providing that the company paid half of the cost of an act of Parliament to authorise transfer of ownership to him.

[30] Part of the Mill Hill Branch of the canal still survives, from the junction near the Lumburn aqueduct to the A390 Tavistock to Liskeard road.