Thames and Severn Canal

• 1. Introduction

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  The Thames and Severn Canal cuts through one of England's most dramatic landscapes, climbing the steep Cotswold escarpment before burrowing beneath its summit to emerge near the headwaters of the Thames. Completed in 1789, it was built to do something no waterway had done before: physically join England's two great rivers, connecting Bristol and the Midlands with London in a single navigable chain. At 28.7 miles long, with 44 locks and a tunnel that was the longest in Britain at the time of its opening, it was an engineering undertaking of genuine ambition. Yet the canal's history is one of constant struggle. Water leaked through porous limestone almost from the day it opened. Trade took routes that made the canal redundant. By 1927, most of it was abandoned. What drives the story of the Thames and Severn Canal is the gap between the scale of what was built and the difficulties that haunted it from the start, and the question of whether twenty-first-century restoration can finally deliver what the eighteenth century could not.

• 2. Digging Through the Cotswolds

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  John Priddy, previously engineer for the Stroudwater Navigation, was likely the first to survey a route for the new canal, and it was Priddy who suggested the terminal points of Wallbridge and Lechlade that the final canal would use. Robert Whitworth then examined two possible alignments, and the route chosen followed the Golden Valley rather than the River Coln valley, largely because Cirencester was expected to offer excellent water supplies. That expectation turned out to be wildly wrong. The estimated cost of the whole project came to £127,916, and most of that was pledged within three weeks of the proposal. Parliament authorized the canal on the 17th of April 1783. Josiah Clowes was appointed head engineer and was paid £300 per year. His reputation grew so much from the work that he became highly sought after in the final years of his life, though he left before the canal was finished to work on Dudley Tunnel. The trickiest part of the construction was the tunnel at Sapperton. There was debate about whether to build it for narrow boats or broad boats, and the decision came down on the side of broad: 15 feet wide and 15 feet high. Work began at the start of 1784 and was expected to take four years. It actually took five, finishing in April 1789. Twenty-five shafts were sunk along the tunnel's course to allow workers to dig from multiple faces at once. The first section of canal, 4 miles from Wallbridge to Chalford, had opened in January 1785, while the rest was still being built. The final section, the 16-lock descent to Inglesham on the Thames, was finished in November 1789. By that point the total cost had reached £250,000, nearly double the original estimate.

• 3. The Water That Would Not Stay

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  Almost nothing about the summit level's water supply worked as planned. The River Churn, which flows through Cirencester, was measured at 1.7 million imperial gallons per day; the calculation made at the start of the project had put that figure at more than ten times higher. The summit level was losing around 1.1 million imperial gallons per day through the porous limestone beneath it, and engineers estimated that only about half of daily requirements could actually be met from available sources. A Boulton and Watt steam engine was installed at Thames Head in 1792 to pump water into the canal. An extra shallow lock was added at Boxwell so that the canal level could be dropped beyond it, allowing more water to be drawn from Boxwell springs. Springs breaking through the clay lining of the canal bed made leakage worse in summer, when the springs themselves receded and left holes that bled water faster than supply could replace it. One measure to reduce water consumption was shortening the locks by 20 feet, which gave them an unusual double-headed shape. At King's Reach, just east of Sapperton Tunnel, the canal was lined with concrete rather than puddle clay. Engineer A. Brome Wilson had pipes installed to bring water from underlying springs back into the canal above the waterline. None of these fixes fully solved the problem. They reduced it to a level that was adequate only because the volume of traffic never reached what the builders had hoped for.

• 4. Trade That Never Came

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  The canal was conceived to carry cargo between Bristol and London, and between the Midlands and the capital, but neither trade route materialised in the way its founders anticipated. On the western side, the River Severn was itself difficult to navigate until the Gloucester and Sharpness Canal opened in 1827. On the Thames to the east, the upper river between Oxford and Lechlade was barely navigable after 1855. The Kennet and Avon Canal, which opened in 1810, offered a much shorter Bristol-to-London route and took most of that trade. Midlands traffic to London found the Grand Junction Canal considerably more direct. What the Thames and Severn actually carried, for most of its working life, was Forest of Dean coal to towns along its own banks. Even that trade came with constraints: the North Wilts Canal, which eventually linked Thames and Severn traffic to bypass the upper Thames, was only 7 feet wide, far narrower than the rest of the waterway, and that bottleneck limited cargo income. The proprietors actively discouraged pleasure boats by setting a toll of £1 per lock for leisure craft, an amount equivalent to over £120 today.

• 5. Railways and Abandonment

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  Railway competition arrived in 1836 when the Cheltenham and Great Western Railway proposed a line through the region. The canal company opposed the scheme and extracted compensation of £7,500 over the following four and a half years. The railway opened as far as Kemble in 1841, and for a brief period the carriage of construction materials for the line actually boosted the canal's toll income. The Great Western Railway then absorbed the line and drove a new tunnel at Sapperton, opening a full route to Gloucester in 1845. Canal toll revenue, which had stood at £11,000 in 1841, had fallen to £2,874 by 1855. In 1893, the canal company announced that the section between Chalford and Inglesham would close with just two days' notice. A trust was formed by act of Parliament in 1895, drawing in representatives from canal companies, river authorities, and several county and district councils, with powers to raise £15,000. The canal briefly re-opened in March 1899, but water shortage on the summit level closed it again almost immediately. Gloucestershire County Council took it over on the 2nd of July 1901, the first instance of a public body taking over a waterway in the public interest in Britain. Negotiations begun in 1925 led to formal abandonment of the Chalford-to-Inglesham section in 1927. The Stroudwater Navigation held on until 1933, and its own canal closed in 1941.

• 6. The Long Road to Restoration

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  Ronald Russell's 1972 book Lost Canals of England and Wales helped prompt a wave of restoration interest across England. That same year, volunteers formed the Stroudwater Canal Society, which grew into the Cotswold Canals Trust by 1975. An early success came in 1979, when lobbying persuaded Gloucestershire County Council to rebuild a damaged bridge at Daneway rather than replace it with a low-level causeway that would have permanently blocked the route. In 1991, the trust commissioned Sir William Halcrow and Partners to assess restoration of the canal's eastern end. Grants of £250,000 from Gloucestershire County Council and £125,000 from North Wilts District Council helped persuade the Department of the Environment in 1997 to agree to build a navigable culvert beneath the planned Latton Bypass. The culvert now sits buried, waiting for restoration work on either side to reach it. In 2001 the Cotswold Canals Partnership was formed. By 2002 the estimated restoration cost for both canals stood at £82 million. Charles, Prince of Wales, visited the canal in his role as patron of the Waterways Trust. A Heritage Survey costing £60,000 was funded by the Inland Waterways Association, and a Community Development Plan and Visitor Management Strategy cost a further £30,000, all required as pre-conditions for a major Heritage Lottery Fund bid. At the end of 2003 the Heritage Lottery Fund awarded a provisional grant of £11.3 million. By the time the grant was confirmed in January 2006 it had grown to £11.9 million, and the South West of England Regional Development Agency added £6 million in match funding. British Waterways pulled out of the partnership in 2008. Stroud District Council stepped in as project leader, and a new body, the Stroud Valleys Canal Company, was created in March 2009 to hold and manage the waterway's assets. An additional £800,000 from the Heritage Lottery Fund arrived in December 2012 to extend restoration to Stonehouse and Bowbridge. Prince Charles returned on the 2nd of February 2018 to cut a ribbon at Wallbridge Lower Lock, marking the reconnection of the Thames and Severn Canal with the Stroudwater Navigation.

• 7. Engineering the Return

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  Phase 1a of the restoration covered about 6 miles centred on Stroud, restoring 10 locks, rebuilding 10 bridges, and reinstating around 2,100 metres of filled-in canal. At Capels Mill, the canal bed had been used as the route for the Stroud Bypass in the 1980s, so a diversion had to be constructed through land that served as a landfill site in the 1960s and 1970s. Some 355 yards of new channel was built, partly edged with sheet piling. After passing through a railway viaduct, a retaining wall made of concrete piles drilled between 30 and 49 feet into the ground reaches 35 feet at its highest point. Domestic rubbish removed from the site was covered with 2 feet of crushed recycled concrete, a layer of Bentomat geotextile, and then topsoil, with tubular vents to release any methane. The new section was filled with water and formally completed on the 2nd of June 2013. An evaluation cruise on the 10th of November 2017 saw the maintenance boat Wookey Hole carry Heritage Lottery Fund assessors, the Mayor of Stroud, and senior trust and council representatives from The Ocean at Stonebridge to Bowbridge Lock, stopping for lunch at Upper Wallbridge Lock. Phase 1b, now known as Cotswold Canals Connected, faces a more complicated set of obstacles: the canal route was severed by both the M5 motorway and the A38 trunk road, and the River Frome and Oldbury Brook have both been diverted into part of the canal bed since abandonment. A £4 million grant from Highways England in May 2019 is funding a tunnel under the A38 roundabout. Phase 1b is expected to be completed by 2028. Phase 3, the central section linking Brimscombe Port with Gateway Bridge via Sapperton Tunnel, faces the hardest challenges: the tunnel is blocked by two rock falls covering sections cut through fuller's earth, which expands when wet. One option being considered is to restore the canal as a narrow waterway 7 feet wide rather than the original 13 feet, which would reduce the cost of replacing some 30 bridges and make the collapsed tunnel sections more manageable.

• 8. Roundhouses and a Royal Navy Captain

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  Five circular canal cottages survive from the 1790s along the route and are listed buildings. Each stands three floors tall. The ground floor served as a store with its own outside access. An exterior staircase leads to the first floor, which measures around 16 feet 10 inches across and was fitted with a cooking range for the occupant. A staircase built between the inner and outer walls spirals to a circular bedroom on the second floor. Their roofs varied: some were pointed slate, others were capped with lead cones that collected rainwater for drinking. The roundhouses were built for lock-keepers and lengthsmen but were reportedly unpopular because circular rooms made it difficult to find furniture that fitted. They stand at Lechlade, Marston Meysey, Cerney Wick near Latton, Coates close to the eastern portal of the tunnel, and at Chalford next to lock 13. In 1953, C. S. Forester set part of his novel Hornblower and the Atropos on the canal. His protagonist Horatio Hornblower, a Royal Navy captain, travels the waterway to London during the Napoleonic Wars, helps leg the boat through Sapperton Tunnel, and takes the helm after the postillion responsible for the horses is injured.