Thames Estuary Maunsell Forts

Nore Fort was the nearest of the Maunsell forts to the shore, situated north east of Sheerness on the Isle of Sheppey. Built at the same time as Shivering Sands and Red Sands it was also built with the same configuration and design.

It was abandoned by the army when the War ended, though the fort was maintained for several years afterwards.

The fort was damaged by a storm in 1953 and 2 months later a ship vered off course destroying two of its towers. Four people were killed in this accident and soon after, all three forts were abandoned to the elements. As this fort was closer to land, very close to the Thames shipping lane, it was dismantled in 1959.

The metal superstructure was recovered for scrap and the concrete bases were towed and dumped near Cliffe on the Hoo peninsular, where they can be seen today in low tide.

One concrete base remains intact along with the stumps of its four pillars – one can get a good idea of the size of the concrete foundations.

If you look out northwards out into the Thames estuary from the north Kent coast, on a clear day, two clumps of rectangular blocks can be observed. These are the Shivering Sands and Red Sands offshore forts that were built during the Second World War to counter attack enemy planes that were relying on the safety of the Thames estuary to come in to bomb London.

On a really clear day, an even stranger apparition appears way out on the horizon – seemingly there’s a pagoda out there in the estuary! This is in fact Knock John naval fort, again built during the Second World War to protect the important shipping line from enemy ships and aircraft.

The excursion took place on a RHIB (Rigid Hulled Inflatable Boat) that has been especially designed to take visitors out to see the sights along the north Kent coast. The boat was operated by Bayblast who specialise in this kind of excursion. Our excursion was to start at Herne Bay.

Looking out to sea, the recently built Kentish Flats wind farm is unavoidable. If you look really carefully, right on the horizon, you can just about see a cluster of dark objects – this is in fact Shivering Sands fort, one of the locations that we were about to go out to visit.

The first thing we were to see on our journey was the end of Herne Bay pier. When originally built, Herne Bay Pier (one of three built for the town) was the second longest pier in the country, measuring 1147m in length, with South End on Sea being the only longer pier in the country. It was designed with both promenading and also to allow steamers to dock for passenger services.

It closed and reopened at various times during its life but the final blow came when the pier from the pavilion built at its shore end was closed as it was deemed to be in an increasingly dangerous state. The remaining length was demolished in 1979, but curiously the very end of the pier was left intact. Today, the structure is dangerous to board, but nevertheless remains, never to be connected to land again.

Being so close to shore, it is a popular location for small boats and jet skis to visit.

Once we were out of the harbour area, where there were many small boats and jet skiers, we powered up to our maximum speed of 25 knots (according to the GPS). For about 20 minutes, we skimmed over the sea, which was incredibly calm. In fact, I’ve never been on a boat when the sea is this calm! As we traveled along, we skirted around the Kentish Flats wind farm, the largest wind farm in the UK.

The Thames estuary is a very busy shipping lane and during our journey, several container ships and ferries intersected our path. As we travelled over their wake, the boat momentarily left the water only to come crashing down the other side of the wave – the only waves we were to experience diring the entire trip!

As there was a haze on the horizon, Knock John fort wasn’t visible for a while but then, appearing like a pagoda designed during the industrial revolution, it appeared on the horizon and slowly loomed into view.

When the Germans started bombing London, it was quickly realised that there was a large area along the Thames estuary, which was undefended. Planes could approach the city and get quite close before having to fly over land so it was decided to provide some off shore defence platforms which would be permanently manned and provide artillery support.

Several platform designs were considered for what was originally called the Thames Estuary Special Defence Units. The platform that was eventually built was designed by architect Guy Maunsell and today, these forts are known as the Maunsell Forts.

The platform was basic in design. Two hollow re-enforced pillars were built, in which several “rooms” were built for the accommodation of 100 men. On top of the two pillars, a platform about the size of a basket ball pitch was placed on which several gun placements could be mounted. The armaments were 3.75 inch AA guns and Bofors 40mm guns. On top of the gun platform a small upper deck was constructed and on top of this a radar platform was built.

Construction work started in 1941, in dry docks where a pontoon barge was constructed on which the two pillars and gun platform was then mounted. The pontoon barge was then towed out to its desired position and the barge flooded. The whole fort would then sink to the ground where it would become firmly fixed to the seabed.

Knock John reached its final position and was sunk on 1st August 1942. It was the forth and last of its kind. The other three were, in order of placement, Roughs Tower, Sunk Head Tower and Tongue Sands. Tongue Sands was destroyed by a storm in the mid-1990s.

Roughs Tower was occupied in 1967 by Roy Bates and his family. He declared it as the independant principality of Sealand on September 2nd, 1967 and is occupied to this day by the crowned prince Roy. Sunk Head Tower was destroyed by the military on 21st August 1967, using 2,220 lbs of explosives in case someone else had similar ideas and to prevent pirate radio stations operating from the platform.

The fortress was designed to be self sufficient for over a month – which was important as the rough weather in the estuary often made it inaccessible for long periods of time.

The platform was in operation the moment it was sunk – the first compliment of 100 men had boarded the platform shortly before it was towed to its working location. It’s hard to believe today that so many people would live on such a remote location.

After hostilities ended, the platform was vacated but was maintained until 1956 when it was officially abandoned. It was believed at the time that the elements would quickly claim the platform and that they would be of little use to anyone else.

Nothing could be further from the truth. During the 1960s, when the only radio broadcasting in the UK was the BBC, a loop hole in the law meant that pirate radio stations could broadcast offshore if they were more than 3 miles beyond the coast. First boats were used, then it was realised that the offshore platforms could be used.

A succession of radio stations started broadcasting from these platforms. On 27th October 1965, Radio Essex started broadcasting from the platform and continued broadcasting until 6th October 1966, when it was renamed BBMS (Britain’s Better Music Station), which ceased transmission on 25th December 1966.

Today, the platform stands silently where it has stood for the last 60 years. It has now been welded shut and will no doubt remain in its current location for many more years.

When the construction of the four naval forts was completed, which were primarily designed to protect shipping, it was decided to built three more forts closer to London primarily to protect the city from aircraft.

Again, Maunsell was commissioned to design these forts. As the tidal conditions closer to shore were different from that found further out at sea where the naval forts were positioned, a different method of foundation was required for the army forts.

Essentially, concrete foundations were created, again in dry dock. These were floated out to position and the concrete bases were allowed to sink. These would bury themselves into the soft sand below thus providing a firm foundation.

Each army fort was similar in construction. There were 7 towers in total. A central control tower around which six other towers, each with a specific function was placed. There were four 3.7in gun towers, a single Bofors tower and a search light tower. Each tower was connected to at least one other tower in the fort by steel walkways.

Construction of the army forts started in August 1942 and was completed by December 1943.

As with the navy forts, the structures were abandoned soon after hostilities ended and were maintained in case they may be needed until the mid 1950s when they were abandoned by the governnment.

Although originally having 7 towers, Shivering Sands now only has six towers. In 1963, during heavy fog, a ship (Ribersborg) veared off the nearby busy shipping lane collided with the tower causing it to collapse.

The tower that was isolated by the accident has since been fitted with equipment by the Port of London Authority to measure wind and tides and also the long term change in sea level.

In 1992, a buoy was placed nearby to replace this functionality as the tower was by then deemed to be unsafe to use.

As with the other forts, pirate radio stations used the location. Shivering Sands became the operational base for pirate radio stations. First, on 7th May 1964 on 194 metres came Radio Sutch, operated by the famous Screaming Lord Sutch. He soon tired of the radio station however and Screaming Lord Sutch sold the station to his manager Reg Calvert in September 1964.

In 1965, the platform was boarded and the station went of air for a few days during a dispute over the station’s ownership, As a part of this dispute Reg Calvert was shot dead, but the station went back on the air soon afterwards, finally becoming silent in 1967.

In August 2005, artist Stephen Turner spent 6 weeks alone in Shivering Sands searchlight tower (the one in the foreground in the picture above) “an artistic exploration of isolation, investigating how one’s experience of time changes in isolation, and what creative contemplation means in a twenty first century context”. He wrote a blog documenting his stay there.

The image above shows the single stump that remains of the tower that was destroyed in the accident. The stillness of the sea causes the other towers to be reflected in an eerie fractured way. In the distance, Kentish Flats wind farm can be seen between the forts and the Kentish shore.

Approaching Red Sands on the journey from Shivering Sands, the construction of this fort can be seen to be very similar to Red Sands. A central command tower surrounded by five other towers in a circle around it, with the searchlight tower slightly removed from the others.

As with Shivering Sands, the towers would have originally all been interconnected by steel walkways, but these have long since been removed for safety.

As with the other offshore platforms, after the war ended, pirate radio operators eagerly boarded the platforms and set up their tall transmitter masts – the configuration of the forts was ideal for such a construction.

First it was Radio Invicta, commencing on 29th July 1964, broadcasting from 6am to 6pm on 306m – the transmission times were limited as overnight transmissions would have been swamped out by a foreign radio transmitter using the same frequency. The station went off air in February 1965 and the fort was soon taken over by KING Radio, transmitting on 238m.

Then on 25th September 1965, Radio 390 took over with a more easy listening kind of programme – light jazz and Mantovani and his Orchestra could regularly be heard all over the south east of England on their 35KW transmitter. All stations were eventually closed in 1967 when the UK changed the law with regard to radio broadcasting.

Recently, Red Sands has been under threat of possible demolition, being considered a danger to the nearby shipping lane. A group of enthusiasts feel this would be a terrible loss to our herritage so recently, a group have gotten together to see if something can be done with Red Sands fort to preserve and indeed introduce new people to the historic value of the forts.

Project Redsand have recently performed a survey which has revealed that the forts are in remarkably good condition under water for their age. They are currently beginning work on the restoration of one of the fort towers.


1 Comment

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One response to “Thames Estuary Maunsell Forts

  1. Frederik Birket-Smith

    Hi there,

    just read you interesting blog about the sea forts of WW2.

    I’m currently writing my master thesis on pirate radios from Roskilde University. If possible, I’d like to use some your sea fort pictures.

    Please contact me on:


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