Caen Hill Locks - Devizeson the Kennet and Avon Canal

Recognised as one of the Seven Wonders of the Waterways

The 29 locks rise of 237 feet in 2 miles. This makes it the steepest flight of locks in Britain. The gradient is a staggering 1 in 44. Navigating all 29 locks (22 to 50) takes an average of 5 to 6 hours in a canal boat. With the locks in your favour and volunteers on hand to assist, it can be done in under five hours.

Caen Hill Locks are one of the most famous and dramatic lock flights on Britain’s inland waterways. Located near Devizes in Wiltshire, they form a central feature of the Kennet and Avon Canal and are widely regarded as one of the greatest achievements of canal engineering in England.

For canal boat users, Caen Hill is both a navigational challenge and a memorable highlight, offering historic significance, impressive scale, and stunning views across the Wiltshire countryside.

Engineers and Dates of Construction

The Kennet and Avon Canal was constructed to link the River Thames at Reading with the River Avon at Bristol. The section including Caen Hill was built during the late 18th and early 19th centuries.

Key details:

• Main engineer: John Rennie the Elder
• Construction period of the canal: 1794 – 1810
• Caen Hill Locks completed: 1810

John Rennie was one of Britain’s most respected civil engineers, also responsible for major bridges, docks, and waterways. At Caen Hill, he was tasked with overcoming a significant change in elevation within a relatively short distance.

During construction, a tramway was built to form a trade link Between 1801 and 1810,  this ran from Foxhangers to the top, whilst the locks were built, there still remains some small parts of the tack in the towpath arches of the road bridges over the canal.

Between 1829 and 1843, the flight was lit at night by gas lights.

Why Caen Hill Was Chosen for the Lock Flight

The location of Caen Hill was dictated by geography rather than convenience. The canal needed to climb the steep escarpment between Devizes and Rowde to maintain a viable route across Wiltshire.

This location was chosen because:

• The land rose sharply west of Devizes
• No suitable river valley existed to provide a gradual ascent
• A concentrated flight of locks was the most practical engineering solution
• The summit pound could be supplied with water via reservoirs

As a result, engineers designed a long series of closely spaced locks rather than a winding contour canal.

The Structure of Caen Hill Locks

The Caen Hill complex consists of 29 locks in total, raising boats approximately 237 feet (72 metres). These locks are arranged in three distinct sections.

Bottom Locks: Numbers 22 to 27

The lower section consists of six locks that lift boats from the lower canal level towards Devizes.

• Locks 22 to 27
• More widely spaced than the main flight
• Act as a steady approach to the main climb
• Surrounded by open countryside

This section allows crews to prepare for the more intensive lock work ahead.

The Main Flight: 16 Locks 29 to 44

The central and most famous part of Caen Hill is the main flight of 16 consecutive locks, numbered 29 to 44.

• Locks are directly back-to-back
• Short intermediate pounds between locks
• Large side pounds to maintain good levels of water supply
• Runs in a straight line up the hillside
• Creates an iconic stepped appearance

This design was chosen to conserve water and space. Side ponds were originally used to reduce water loss, although they are no longer operational today.

A back pump was installed at Lower Foxhangers Lock 22 in 1996 which is capable of returning a staggering 7 million imperial gallons of water every day, from Foxhangers to the top of the flight. If you like, this is a whole lock-full of water every eleven minutes!

For canal boat users, this section requires careful planning, teamwork, and time, but rewards crews with exceptional views and a strong sense of achievement.

Top Locks: Numbers 45 to 50

The upper section consists of six locks that complete the ascent and lead onto the summit level.

• Locks 45 to 50
• More spaced out than the main flight
• Mark the transition to easier cruising
• Lead towards the Devizes Wharf area

Once through the top locks, the canal becomes calmer and more level, offering relief after the demanding climb.

Historical Decline and Restoration

Like much of the Kennet and Avon Canal, Caen Hill fell into disuse during the late 19th and early 20th centuries due to competition from railways and roads.

Key milestones:

• Commercial decline by the late 1800's
• Locks became derelict and unnavigable
• Major restoration efforts began in the mid-20th century
• Caen Hill Locks fully restored and reopened in 1990

The restoration was one of the largest canal engineering projects of its time and played a crucial role in reviving the entire Kennet and Avon Canal.

Caen Hill Locks Today

Today, Caen Hill Locks are a major attraction for:

• Canal boat users
• Towpath walkers and cyclists
• Heritage and engineering enthusiasts
• Visitors to Devizes

The locks are fully operational and supported by volunteer lock keepers during busy periods, helping boats ascend and descend safely.

Why Caen Hill Locks Are So Important

• One of the longest continuous lock flights in Britain
• A major engineering achievement by John Rennie
• Central to the success of the Kennet and Avon Canal
• A defining landmark of Devizes
• A must-experience challenge for canal boat users

Conclusion

Caen Hill Locks are far more than a series of locks; they are a testament to early 19th-century engineering ambition and skill. Carefully designed by John Rennie and completed in 1810, the locks allowed the Kennet and Avon Canal to overcome a formidable change in elevation. Today, divided into their three distinctive sections, they remain one of the most impressive and rewarding experiences on the British canal network.