The astonishing find was made by workmen during the widening of a section of road in Prittlewell near Southend-on-Sea in 2003. Artefacts have been analysed by a team of experts who believe the remains could be that of Seaxa, brother of Anglo-Saxon King Saebert. Sophie Jackson, director of research and engagement for Museum of London Archaeology (Mola), said it is the earliest dated Christian Anglo-Saxon princely burial in the country.
Archaeologists estimate it would have taken 113 working days to build the chamber, which contained exotic artefacts from around the world.
Ms Jackson said: “I think it’s our equivalent of Tutankhamun’s tomb.
“It’s getting an intact version of this and seeing how everything is positioned and what he’s got with him.”
She said the site had been fully excavated because, once discovered, it was vulnerable to potential theft.
Artefacts uncovered include a stringed musical instrument called a lyre, a 1,400-year-old painted wooden box and a flagon believed to be from Syria.
It is the first time a lyre has been recorded in complete form, and the box is the only surviving example of painted Anglo-Saxon woodwork in Britain.
Other finds included the gilded silver neck of a wooden drinking vessel used for wine, and decorative glass beakers.
Ms Jackson said: “I think the thing that’s so strange about it is that it was such an unpromising looking site.
“It’s between a bit of railway and a bit of road, essentially a verge. It’s not where you’d expect to find it.”
Carbon dating indicated that the male died between 575AD and 605AD, so could not have been King Saebert, who died in 616AD.
Fragments of adult tooth enamel suggest he was over the age of six, and the size of the coffin and placement of items within suggest he was about 5ft 8in.
Ms Jackson said it was possible it was the king’s brother, Seaxa, adding: “That may also not be correct, but that’s the best guess.
“There’s a lot of debate about whether he was a fully-fledged hairy beast Saxon warrior, or younger,” she said.
“Had he died before he could really prove himself as he could have been buried with more kit?
“The presence of artefacts from other kingdoms suggest wealth.
“It’s a really interesting time when Christianity is sort of creeping in and this is all possibly before Augustinian sent his mission to Britain to convert the country to Christianity so they would have been just on the transition between having pagan burials with all your gear but also having these crosses.”
The chamber, which was about 13ft by 13ft and around 5ft deep, contained some 40 artefacts.
Some of them will be displayed at an exhibition at Central Museum in Southend which opens to the public on May 11, and research will also be published in two books.
The project was funded by Southend-on-Sea Borough Council and Historic England.