The Thames Barrier

A masterpiece of British engineering and design protecting London since 1982

In 1972 Londoners were asked “If London flooded tomorrow, would you know what to do?” Well most of us didn’t. We were aware of the Thames and its tides of course but hadn’t given the possibility of flooding much thought. Not so the government, they were clearly worried and began a series of measures to raise public awareness. There were a number of public service broadcasts, articles in the press, and notices delivered to thousands of residents in low lying areas close to the river. Living near the Royal Hospital, Chelsea at the time, we received an A5 sized notice warning us about possible flooding from the sewers. Not a happy prospect. There were instructions on one side and ‘HELP’ written in big red letters on the other, which we were supposed to stick on, or wave out of an upstairs window. Luckily we never had need of it and ten years later the Thames Barrier had been completed and London protected for years to come.

Always on the alert, and taking into account information from satellites, weather ships, oil rigs and coastal stations, the Environment Agency can forecast potential danger of flooding up to thirty-six hours in advance. When computer calculations based on a combination of high spring tides, expected tidal surges, low atmospheric pressure and strong winds indicate a risk of flooding, the team at the Thames Barrier are ready to set the flood defences in motion. However, the final decision to close the barrier rests with the Thames Barrier Duty Controller.

At the time of writing the most recent closures have been on Sunday September 30 and Monday, October 1st, 2019. The Barrier has now been closed 186 times since it first came into operational service in 1982. Since its first test in November of that year, this masterpiece of British design and engineering has been operational, ready to be put into a defensive position to protect 125 square kilometres of central London from flooding. It stretches 520 metres across the Thames at Woolwich and its shining, hooded piers are a striking feature of the landscape.

A feature of the landscape: the shining hooded piers of the Thames Barrier

London has been flooded throughout its history both as a result of rising sea levels and the progressive tilting of South East England. The problem was exacerbated by the gradual embankment of the Thames in the second half of the nineteenth century, which channelled the river into an ever smaller space, so raising its level in central London.

The severe 1953 flood that struck coastal areas along the North Sea and particularly Canvey Island where fifty-nine people were drowned and 13,000 evacuated from their homes, and an earlier flood that had struck the heart of London itself in 1928, drowning fourteen people and making thousands homeless, began to concentrate minds on devising proper flood defences for the capital.

In 1954 Hansard reports that the Waverley Committee set up by Parliament, proposed that: “As an alternative to raising the banks”, which would have been likely to obscure stretches of the river from view, “the possibility and cost of erecting a structure across the Thames, which could be closed in a surge should be urgently investigated.”

However, it was not until a further review, conducted by Sir Hermann Bondi in 1967, taking the project forward, that any action took place. The site for the barrier was then fixed at Woolwich, from New Charlton across to Silvertown as part of an overall plan which included the raising of the river banks further downstream. Then a design had to be chosen.

From the forty-one plans considered, it was engineer (Reginald) Charles Draper, working with Rendel, Palmer and Tritton, who came up with the chosen solution. It was a revolutionary idea inspired by a simple gas cock in his home. He was photographed in 1981 by Gordon Gahan, overlooking the as yet incomplete barrier, proudly holding a gas ball valve like the one that had given him the idea: a poignant image as Charles Draper sadly died before the work was finished.

(Reginald) Charles Draper © Gorden Gahan

There followed ten years of modelling, testing, refinement of the design, and actual construction; longer than planned as it was the first project of its kind. There were also funding problems and a number of serious industrial disputes. The Thames Barrier finally became fully operational in November 1982 when it rose for the first time, and was officially opened by the Queen in May, 1984.

Towards the end of its construction, intrigued by reports of its innovative design, we took our young sons to see how the work was getting on. Not easy. There were no signposts. But armed with an A to Z map we got quite close and luckily spotted a workman in a hut on a nearby building site. Clearly we were not the first to have been on this trail as he produced a photocopy of a rough map with directions to a viewpoint at the top of some metal stairs. Breathtaking. The barrier really was as impressive as it had been made out to be.

These days you can see the barrier from the Thames Barrier Park, in Silvertown north of the river; the Thames Barrier Information Centre, near Woolwich, on the south side; or from a boat passing though the barrier itself. It was this last view that really brought home to me the massive achievement of all those involved with the building of London’s most important defensive structure.

Approaching the barrier from upstream, its distinctive gleaming metal-hooded piers seem to rise up through the water like dragon’s teeth warriors each with a cyclopesian eye. The closer you come, the more impressive they are.

Approaching the Thames Barrier from upstream
Reflections of the river in the round window at the top of one of the piers

The six main steel gates are D-shaped. When set in the defence position their rounded surfaces face downstream and their flat surfaces upstream. Known as rising sector gates they normally lie flat at rest in concrete sills on the river bed, allowing free movement of shipping and normal tidal flow. Operated by a hydraulics system in the towers they can be held in four positions: rest, defence, underspill and maintenance. When the barrier is used or tested, the gates are moved into place shortly after low tide to hold back the flow of the river on the upstream side and to stem the incoming tide downstream.

The Barrier fully open with gates at rest on the river bed
The Barrier fully closed with the gates in the defence position

A strong tidal surge will build up considerably more water on the seaward side so that when the tide begins to flow out the gates are gradually moved into the underspill position, allowing a carefully controlled flow upstream so as not to create a rush of water. The gates can only be lowered into their resting position once the levels on each side are the same. They can also be raised and held above the water to allow access for maintenance. In addition, there are four non-navigable gates set close to the river banks.

Two of the gates in the underspill position allowing water from the seaward side to flow upstream underneath
Controlled flow of water flowing upstream from beneath the gates in the underspill position

The decision to close the barrier is made by the Duty Controller after assessing reports from a team of flood forecasters. Taking into account the flow into the tidal Thames at Teddington, the predicted tide levels and weather conditions that can affect the height of a tidal surge, forecasters can predict the likely risk up to thirty-six hours in advance. The control room is staffed at all times. If necessary, the barrier will be closed roughly four hours before the peak of an incoming surge. Each steel gate takes ten to fifteen minutes to close, and the whole barrier an hour and a half.

Flood forecaster Alan with the Thames Barrier in the background

Flood forecaster Alan, who also runs the barrier’s Twitter feed explains that though they run monthly test closures they’ve “never had to close between May and August to protect London against a high tide since the Thames Barrier became operational in 1982. It doesn’t mean that we’re not on the lookout though.”

This year’s annual test closure was due to take place on September 29th but had to be cancelled after particularly high tides meant that the barrier had to be closed twice in three days for real, to protect London from flooding.

Workboat PROWLER moored with another craft at pier 8.

As mentioned earlier, the barrier has been closed to protect London 186 times but the exceptionally high number of fifty closures in the 2013-14 flood season caused real concern. Doubts were raised that the barrier would be able to protect the capital beyond its originally estimated lifespan of fifty to sixty years. However after a study, Dick Tappin, a member of the original team who created the barrier, wrote in 2014 that “The Thames Barrier remains fit for purpose” and provided it is properly maintained, “it will remain so to at least 2070.” This was backed up by a government study revised in 2016 saying that the Thames Estuary defences, “which include the Thames Barrier and 350 kilometres of flood walls and embankments, smaller barriers, pumping stations and flood gates” will continue to protect London throughout the century. We are fortunate that the marvel of modern engineering that is the Thames Barrier will be with us for a while yet.

Approaching the Thames Barrier from the footpath near Greenwich

For the main source of my article, with understandable, technical information and explanatory diagrams, click on the: Thames Barrier and follow @AlanBarrierEA for up-to-date info. An internet search will reveal many striking images of all kinds of ships passing through the barrier including some by Photographer Rob Powell on

All Hallows by the Tower

The oldest church in the City, inextricably bound up with the Thames and the Port of London

Just a few steps away from the tourist-thronged Tower of London stands a church, founded in AD 675 as a chapel of the abbey of Barking, that is older than and steeped in as much history as its famous neighbour. And yet only a comparatively small number of visitors make it up to the South Entrance in order to explore within.

Despite standing by a busy main road, it’s the quietness that strikes you as you step inside, though from time to time there is the faint rumbling beneath your feet of a nearby underground train. Yet its situation by the Thames, with the parish’s southern boundary being in the middle of the river, has naturally had an important effect on its life. And the Mariners’ Chapel in the south aisle reflects this.

The altar in the Mariners’ Chapel

The altar, panels, model ships, memorial plaques, and stained glass windows all bear witness to the church’s links with the sea, the river, and the Port of London. The Custom House, quays and docks were on the riverside close by.

The wooden screen behind the altar commemorates the links between the Port of London Authority and All Hallows by the Tower. In the centre of the altar a candle burns for “all seafarers who are in danger or distress”, and a prayer for all those, whoever and wherever they are, “exposed to the many dangers of the deep”.

The Crucifix above the altar in the Mariners’ chapel

The crucifix above the altar was made from a piece of wood from the Cutty Sark and the ivory figure of Christ is believed to have come from the captain’s cabin of the Spanish Armada’s flagship.

A fine model of the Cutty Sark above the altar screen catches the light

Model of a barge that used to stand in the front window of a Thames barge builder

Looking around the chapel you will see several intricately made model ships, hanging from arches, placed on furniture or in cabinets. Over the years they have been given to the church as ex votos, symbols of thanksgiving, memorials, or simply by boat builders as they moved premises.

Model of MV Royal Daffodil, a pleasure steamer. Over a number of trips she rescued 9,500 men from the shores of Dunkirk during the Evacuation in 1940
The British Trent Memorial Bell commemorating the nine seafarers who lost their lives in the North Sea on June 3rd 1993

There are a number of poignant memorials, around the church, in the chapel and in the Crypt Museum, including one for HMS Hood, sunk during the Battle of Denmark Strait in the Second World War, with the terrible loss of 1,415 lives, leaving only three survivors. Also on display is the Maritime Memorial Book, established by the Maritime Foundation in 1987 recording the names of those who “have no grave but the sea” to which names can still be added if you search their site. And on June 25, 2019, a Thames Memorial by Clare Newton was dedicated in a moving service to all those who have lost their lives in the Thames.

The Thames Memorial by Clare Newton

The church was bombed on two occasions during the Blitz: first the east end was badly damaged by a bomb in December 1940, and three weeks later the whole building was gutted by incendiary bombs, leaving only the tower and outer walls standing. However, All Hallows was fortunate at this time to have the Reverend Philip Thomas Byard Clayton, nicknamed affectionately ‘Tubby’, as its vicar.

An army chaplain during the First World War he had teamed up with another chaplain, Neville Talbot, creating Talbot House as a refuge for battlefront soldiers, an alternative to the temptations of the town of Poperinge in Belgium, where they could spend their leave. It was known as Toc H, which grew into an “international philanthropic organisation promoting ideals of service, comradeship and reconciliation.” After Clayton’s installation as Vicar of All Hallows in 1922, the church became the guild church of the movement.

On the very day that the church was bombed Clayton at once declared that it should be rebuilt. His enthusiasm and powers of persuasion had a strong impact. The foundation stone was laid by Elizabeth, the Queen consort of George VI, in July 1948. There followed practical donations in the form of various building materials and financial support from all over the world, and the church was re-dedicated in 1957.

During all this time Clayton remained vicar of All Hallows by the Tower and also chaplain to the Port of London Authority. A report in The Guardian on August 4, 1947, describes how he kept “a close eye on anything happening on the Thames” and highlighted his concern about accidents on the Tower beach. Bathing was allowed “when the tide is safe” and there were wardens to watch the children but several accidents had taken place when the beach was closed. He was also worried about the dangers posed by the ‘Iron Gate Stairs’ there. As a special precaution for the August Bank Holiday that year, Clayton arranged for a “voluntary patrol of men” to watch the Stairs from a boat.

The stained glass windows, especially in the south aisle, bear witness to the church’s close association with the sea and the river Thames. As all but two of the seventeenth-century stained glass panels were destroyed during the Blitz, the beautiful stained glass windows you can now see were all made post war. Several of them were donated by the City of London Livery Companies associated with the church.

The Port of London Authority window can be seen above the book shop
The Coat of Arms of the Port of London Authority
Detail of Port of London Authority Window with representations of the Tower of London and surrounding buildings
Detail of the Port of London Authority window: Edward Grobbe Shipowner, 1278 and John Rolff Shipwright, 1432
The window of the Company of the Watermen and Lightermen of the River Thames

The church’s close links with the river can be seen again in the annual ceremony of Beating the Bounds. This is a tradition dating back to medieval times, when parishes processed around their boundaries, beating boundary markers with sticks to mark out their territorial limits. The added interest to the All Hallows’ ceremony is that part of their boundary runs along the middle of the Thames and the beating party “made up of the clergy and the Masters of the livery companies associated with the church, go out on the river in a boat to beat the water with their canes before returning to shore and continuing around the rest of the parish.”

In writing this piece I have concentrated on All Hallows’ close links with the Thames, the Port of London and shipping world-wide. However, there is much more to discover including its architectural history, which dates back to Roman times; its strong association with the Tower of London; its role in the temporary care of bodies of high profile prisoners beheaded on Tower Hill – a list of confirmed executions can be seen here; and its links with America, which will be of particular interest to my American readers.

Memorial to William Penn above an entry door to the Church of All Hallows where he was baptised on October 25, 1644 (c) Alan Levine, USA

Admiral Penn, father of William Penn who founded the colony of Pennsylvania, was also a Member of Parliament at the time and helped to save the church during the Great Fire of London in 1666 by directing some of his men from a nearby shipyard to create firebreaks to protect both St Olave, Hart Street and All Hallows, by demolishing nearby buildings. His son William was baptised in the church and educated in the church school before setting off to America. A further link is that with John Quincy Adams, sixth President of the United States, who married Louisa Catherine Johnson in All Hallows on July 26, 1797.

At ease with its eventful past, wide international links, and place in the fabric of both the City of London and the country, All Hallows welcomes visitors to its services, those in search of history, and those who seek space for prayer and quiet contemplation. It is today a modern, “active and inclusive Christian community”, and its associations and ties with the river Thames remain as strong as ever.

The east-facing window in the north Aisle

Using the link highlighted here, you can find out more about the history of All Hallows by the Tower