Sapperton Canal Tunnel, Gloucestershire

The Sapperton Canal Tunnel is a disused structure along the old Thames and Severn Canal, 3 miles west of Cirencester in the Cotswolds, constructed in 1784, open in 1789 and abandoned around 1933, notable for being the longest tunnel of any kind in the country at the time, at 2.17 miles, until surpassed by the Standedge Tunnel near Huddersfield.

In the decades since, roof collapses at several points have left the tunnel completely impassable, and while there are ambitious plans to restore and reopen it, for now it remains an interesting and photogenic historic relic, its two entrances hidden away in woodland surroundings, reached by footpaths.

Both entrances are ornate structures, the Daneway portal at the west end and the Coates portal to the east, and both are listed buildings. The portals lie along the Wysis Way, a long distance path, so could be visited on a single walk (2.4 miles) of which around half is along roads, or separately, by driving between them.

History

The Sapperton tunnel, named after a nearby village, was constructed by sinking 26 shafts along its length then excavating in either direction, and eventually linking up all the sections, after which the whole tunnel was enlarged and lined with bricks. The shafts later served as ventilation points. The deepest part of the tunnel is 213 feet below ground. The bedrock is a mix of clay and limestone, both of which caused problems; the former is prone to expanding and contracting, the latter to cracking and leaking, so regular repairs were needed, yet the tunnel remained in regular commercial use until 1911. It was still open and navigable for sometime more, until around 1966, before larger roof falls blocked the passage in several places. The canal remains navigable for some distance at the east end, however, and boat tours are sometimes arranged, by the Cotswold Canal Trust; the water level in this section is maintained by a wooden dam a short distance further east.

West Entrance

The west (Daneway) portal can be reached by parking somewhere near the Daneway Inn and walking east along a path, Wysis Way, that runs between the canal - here just a dry, sunken channel - and the River Frome, through a corridor of trees. The river turns away to the north, transported under the canal via a culvert, while the canal bends south and enters the Sapperton Tunnel. The crenellated portal, which was restored in 1996, has elegant brickwork, and was constructed between 1784 and 1789. The tunnel is open, and usually filled with shallow water, around one foot deep.

East Entrance

The east (Coates) portal is reached via a minor road southwest of Cirencester, parking at Tarlton Bridge over the canal then walking a quarter of a mile north along the towpath to the entrance. This section is filled with water, around 4 feet deep, maintained by the dam. The portal is similar in style to the west entrance, though even more elegant, incorporating a pair of Doric columns. Above the portal is Tunnel House, a pub, built in the 1780s for workers on the tunnel and continuing to operate, despite various problems, until 2022. Apart from the path it is accessed only by a narrow, dead-end track so has in recent years suffered from a lack of custom.