Equiano wrote a vivid account of the terror of working below decks as a powder monkey in the heat of battle; specifically in one of her most famous victories over the French fleet at the Battle of Lagos on 17 August 1759, a key incident in the Seven Years’ War.

After decades of research, experts have confirmed that the timbers found under six layers of floorboards in 1995, at Chatham Historic Dockyard in Kent, came from the ship built at the yard in the 1750s, and broken there in the 1830s.

“The Namur was one of the ships that played a vital role in the Seven Years’ War – a crucial episode, as important for this country as the two 20th century world wars, but which has now passed almost entirely from sight,” said naval historian Richard Holdsworth, the leader of the project at the dockyard.

He described the war, which began in 1756 and eventually involved Britain and most of Europe, the west African coast, and North and Central America, as the world’s first global conflict.

“The Namur helped win the British navy mastery of the oceans, which gave the country the world power status that endures to this day.”

The timbers were revealed by chance in 1995 when repair work began on a near derelict Georgian wheelwright’s workshop, one of scores of historic buildings and structures within the yard. The find was described as the best in warship archaeology since the discovery of the Tudor Mary Rose, flagship of Henry VIII, at Portsmouth almost 30 years earlier. But the identity of the ship was completely unknown.

Years of research have not only conclusively identified the Namur but revealed carpenters’ marks proving that the same shipwrights worked on Nelson’s flagship, Victory, also built at Chatham.

The Namur was an exceptional ship. At a time when the working life of most timber ships was about 20 years, she saw more than 47 years of active service, taking part in nine fleet actions – often as the flagship – in three campaigns.

Holdsworth only learned of the Equiano connection a few months ago: “I was drinking coffee at the Maritime Museum, and I was so astonished I almost dropped my cup.”

According to his 1789 autobiography – The Interesting Narrative of the Life of Olaudah Equiano or Gustavus Vassa, the African, which is one of the earliest books published in England by a black author – Equiano came on board as the 14-year-old slave of an officer. He recalled carrying gunpowder to one of the cannons with another boy as powder fell around them from rotten cartridges. “We were also from our employment very much exposed to the enemy’s shots: for we had to go through nearly the whole length of the ship to bring the powder. I expected therefore every minute to be my last, especially when I saw our men fall so thick about me.”

The yard, which at its height employed more than 10,000 people, has been a visitor attraction since its closure. But a new gallery will display the timbers where they were laid almost 200 years ago as part of an £8.4m project to tell the history of ship building on the site.

“I suspect it was no coincidence that so much of the ship was kept here,” Holdsworth said. “This was a critical time in the history of the navy and the yard, when the age of the great wooden ships was just giving way to iron.Turner’s famous painting of the Fighting Temeraire being towed here to be broken was painted just a few years later.

“Chatham forgot it had the timbers, but never forgot the Namur: when the last ship was launched there, the Ocelot submarine in 1962, the programme included line drawings of famous ships built at the yard – and there was the Namur among them.”