A bronze cannon from one of England’s most important protected shipwrecks – the 17th century warship the London – has been revealed by chance on the seabed in the Thames Estuary. The discovery was made by one of Historic England’s licensed divers after being hidden in thick clay and silt for nearly 360 years.  

Links to King Charles II

The London was built at Chatham Historic Dockyard in Kent in 1654-1656 during a time of great political upheaval after the English Civil War (1642-1648) and the First Anglo-Dutch War (1652-1654). The ship formed part of a convoy sent in 1660 to collect Charles II from the Netherlands and restore him to the throne. The protected wreck of the London lies in two parts off Southend Pier in Essex after blowing up in 1665 due to a gunpowder explosion.

Rare underwater diving conditions

Image: Cotswold Archaeology

Steve Ellis, Licensee for the London wreck, who has been diving at the site for 14 years, believes very rare ‘ideal’ underwater conditions came together to reveal the exceptionally well-preserved cannon on the seabed.  

Licensed divers play a vital role in monitoring the condition and recording artefacts of England’s most historic and archaeologically significant Protected Wreck Sites. Historic England grants the licenses on behalf of the Secretary of State for Culture, Media and Sport. Anyone can apply to access a designated wreck site.

Protecting our underwater heritage from thieves 

The cannon is now being included in Historic England’s forensic marking programme, using the latest underwater protective marking technology to deter thieves. Working with MSDS Marine and partners, this scheme is part of Historic England’s wider ‘Heritage Watch’ programme. The forensic marking product was trialled on several Protected Wreck sites around the English coastline during the summer of 2023. This included the marking of several bronze cannon on the 17th century Dutch warship Klein Hollandia. Invisible marking acts as a deterrent to potential criminals because it is traceable. 

Duncan Wilson, Chief Executive of Historic England said: “This amazing discovery will help us to better understand the types of cannons on board the London when it blew up in 1665. They weren’t all the same as some were captured from enemy ships, so there is a complex story to unravel here. Our licensed divers play a huge part in investigating and monitoring our Protected Wrecks at sea, ensuring they are there for future generations to learn from and enjoy.”  

Steve Ellis, Licensee of the London wreck said: “It was so exciting to see the cannon emerge from the seabed after many years of diving the site. This discovery sheds new light on my theories about how the ship may have exploded and how it came to lie in two parts on the seabed.” 

Very poor diving conditions 

Ornate 4cm wide bronze sundial compass.
Image: Steven Ellis

Visibility in the Thames Estuary is often extremely poor – less than half a metre at times – so conditions had to be perfect for the cannon to become exposed suddenly, embedded in clay. Work on the site is particularly challenging due to a highly tidal environment and the wreck’s location next to a busy shipping lane where large cargo vessels regularly pass by. 

The cannon discovery and what it might tell us

The newly discovered cannon on the London wreck is believed to be a Commonwealth medium-sized 8’x6″ Demi-cannon, cast by George Browne 1656 -1657. It is part of a set made for the London which was placed on the lower gun deck of the ship. This type of cannon is larger than a culverin and smaller than a regular 42 pounder (19kg) cannon. 

At the time of its sinking, the London was one of only four English naval ships to have a full complement of 76 bronze cannons. Each gun carriage would have been unique because the London’s guns were not standardised and originated from different countries and different periods in naval history.  

Large cannons were in short supply and were expensive to make, requiring significant amounts of bronze or iron and individual casting. As a result, captured cannons from enemy vessels and from other shipwrecks or decommissioned ships were often used to help equip new warships such as the London.  

Mark Beattie-Edwards, Chief Executive of the Nautical Archaeology Society, said: “For over a decade we have suspected that some of the cannons on board the London were still on the seabed, and now Steve and his team have proved it. The discovery demonstrates just how culturally rich the wreck is, and with the site actively eroding the potential for further similar finds remains ever present.”

Mark Harrison, Head of Heritage Crime at Historic England, said: “Protective marking of this cannon will act as a clear deterrent to those looking to unlawfully lift and remove historic material from Protected Wreck Sites. The new markings will give police the ability to link the offender to the crime scene and implement criminal proceedings.”

Based on historical documents and modern records, it is estimated that around 41 of the 76 cannons that went down with the warship have been recovered.  

Heritage at Risk Register

The London is one of four protected shipwrecks on Historic England’s Heritage at Risk Register. The others are the Rooswijk, Northumberland and the Restoration. 

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