Three main types of canal were developed in Britain in the second half of the 18th century, namely broad canals, with locks 14 feet wide, narrow canals, with locks 7 feet wide, and tub-boat canals. The latter type of canal was developed to pass through land where the gradients were particularly steep and they were principally built in Shropshire and the South West. The complex network of tub-boat canals in Shropshire was characterised by their short length and narrow width. In total, five tub-boat canals were built in the area now known as Telford, these being the Donnington Wood Canal, Ketley Canal, Shrewsbury Canal, Shropshire Canal and the Wombridge Canal.

The tub boats that plied these canals traversed incline planes mounted either in cradles or caissons running on rails, those in Shropshire being fitted with cradles.

As early as the 1780s, canal engineers were searching for means of replacing flights of locks with other devices, such as inclined planes and lifts, and for contrivances, such as cradles and caissons, to carry boats. Today, no inclined planes remain in working order on Britain's canal system but their remains, sometimes obscured by undergrowth and trees, can still be found here and there. Approximately 20 inclined planes were constructed in the South West alone, notably on the Bude and Torrington Canals and the Ridd inclined plane on the latter canal is particularly noteworthy.

In Shropshire, the Donnington Wood Canal ran from Pave Lane, near Newport, through Lilleshall to Donnington Wood. It had branches at Lilleshall and at Donnington Wood there was an inclined plane to the mines. The Ketley Canal connected Ketley and Oakengates, where it linked with the Shropshire Canal, and it had one inclined plane. The Shrewsbury Canal, constructed by Josiah Clowes and later Thomas Telford, ran from the foot of the Trench inclined plane to the centre of Shrewsbury. It contained the renowned iron aqueduct at Longdon and a number of guillotine locks. The Shropshire Canal ran from Donnington Wood to Coalport and it had four inclined planes. The Wombridge Canal ran from Wombridge, via the head of the inclined plane at Trench, to Donnington Wood where it connected with the Donnington Wood Canal. At Trench, access to the Shrewsbury Canal was by means of the inclined plane. To compound matters, the Newport Branch Canal eventually connected the Shrewsbury Canal to the main line of the Birmingham & Liverpool Junction Canal (Shropshire Union Canal) at Norbury Junction.

At first, the inclined planes in Shropshire were self-acting, descending loaded boats hauling up empty ones, and horse gins provided power when the reverse situation applied. However, gins were quickly superseded by steam engines that powered a complicated arrangement of pulleys used in the haulage process. Tub boats were rectangular in plan, 20 feet long x 6 feet 4 inches wide, and were of wrought iron construction. A boat descending an inclined plane entered one of the two chambers, built at a right angle to the canal, where it was manoeuvred over a submerged cradle running on rails. Once in place, the boat was secured to the cradle in readiness for its passage down the plane. The cradle was then hauled over a sill and onto the plane, at which point it was still inside the chamber. When everything was ready it began its descent, which required just a few minutes, and a small number of workmen were able to complete the whole operation.

The best preserved is the Hay inclined plane at Coalport in Shropshire. Here there is a difference of 207 feet between the Shropshire Canal and the bottom of the Severn Gorge where goods were transhipped between tub boats from the canal and barges/Severn trows on the river. It became disused around the turn of the 20th century following which the rails were ripped up and the associated buildings partially destroyed. Following the establishment of the Ironbridge Gorge Museums Trust in the early 1970s, the plane was cleared and the rails were replaced. Volunteer working parties from the Peak Forest Canal Society assisted with this work. Nowadays, a section of the Shropshire Canal and the inclined plane are contained within the Blists Hill open-air museum.

William Reynolds

The inclined plane on the Ketley Canal is commemorated on a halfpenny trade token dated 1792. At this time the government was not issuing sufficient small coinage and employers were quick to exploit government inertia by issuing their own money in the form of trade tokens. Employees were paid using these tokens, which could only be spent at the company shop or exchanged for coins of the realm at some remote location.

The reverse of this token depicts the chambers into which tub boats had to enter to enable them to be manoeuvred over cradles. On the left an empty cradle can be seen at the top of the plane and on the right a workman seems to be operating a control lever. Mounted above the chambers is the arrangement of pulleys that were powered by a steam engine.

William Reynolds, a Shropshire ironmaster from Ketley, surveyed and oversaw construction of the Ketley and Shropshire Canals but the exact date of their opening is uncertain. However, the trade token shows that the Ketley Canal was operational by 1789. Although this canal was only 1½-miles long, the difference in height between the two ends was 73 feet at Ketley Bank. As a result of this difference in height, Reynolds' built what is believed to be Britain's first inclined plane. The function of this canal was to supply ironstone to his Ketley ironworks. In 1816 this works closed and thus the Ketley Canal became unused. It is believed that the inclined plane remained operational for another two years before it too closed.

A rare view of the Hay inclined plane at Coalport, Shropshire, late 19th century. At the top of the plane the two chambers, where tub boats were manoeuvred onto cradles, can be seen and the large structure above housed the pulleys that were used to haul tub boats on the plane. The adjoining building on the right is the engine house and the chimney further to the right marks the location of the boiler house.	1792 halfpenny trade token. Coalbrookdale, the first iron bridge. The obverse depicts a boat, possibly a Severn trow, passing below the famed iron bridge at Coalbrookdale. The wording above the bridge states, ‘ERECTED ANNO 1779. SPAN 100 FEET.’ Around the periphery it is worded, ‘IRON BRIDGE AT COALBROOK DALE. 1792’. The reverse depicts the top of the inclined plane on the Ketley Canal and below it is worded, ‘INCLINED PLANE AT KETLEY 1789’. Material: copper, Diameter: 1 5/32 inch.
The Hay inclined plane at Coalport, Shropshire, April 1975. Members of a Peak Forest Canal Society Working Party are seen here helping to replace the rails on the incline.	The Longdon-on-Tern aqueduct on the Shrewsbury Canal, 25 July 1978. Thomas Telford built this famous aqueduct over the river Tern (a tributary of the Severn) and it is often claimed that it was the first to be built of iron plates bolted together. Nonetheless, this is incorrect as the first iron aqueduct was the Holmes aqueduct on the Derby Canal, which was built by Benjamin Outram. This opened in February 1796 to be followed one month later by Telford’s Longdon-on-Tern aqueduct.
Bottom guillotine lock gate on the Shrewsbury Canal north of Hadley, Telford, 1985. By this time only traces of the winch mechanism can be seen and the counterbalance weights have disappeared.	A tub boat moored on the Shropshire Canal at the Blists Hill site of the Ironbridge Gorge Museum Trust, 1982. It is moored a short distance away from the top of the Hay Inclined Plane at Coalport where there is a 207 feet vertical fall between the canal and the point at the foot of the Severn Gorge where goods to be sent further afield could be transhipped from tub boats into barges/Severn trows on the river. Writing in 1904, Henry Rodolph de Salis stated that there were only about 24 tub boats left but the one shown here is believed to be one of the very few to have survived.