Thu, 16 Mar 2017 17:18 UTC
Curators made the remarkable discovery inside a war-time service envelope with a hand-written note identifying the contents as being from an ancient Egyptian tomb originally built around 1290 BC.
The ancient textile - described as a "curator's dream" by the museum's ancient Egypt expert - was painstakingly unwrapped and dried out by conservators over nearly 24 hours.
It revealed a hieroglyphic inscription identifying the owner as the previously-unknown son of the Roman-era high official Montsuef and his wife Tanuat, and depicting the deceased as the god Osis.
Experts at the museum say the inscription and the recorded deaths of his parents in 9BC has allowed them to date the shroud almost precisely.
The shroud, which is said to be in a "remarkable condition," will be going on display at the end of the month along with other exhibits drawn from the tomb.
More than 100 objects will be going on display as part of the the exhibition, which will chart the full story of the tomb, which was built in the city of Thebes used for the final time shortly after the Roman conquest of Egypt.
They include amulets, coffins, furniture and statues as well as inscribed mummy bandages, mummy tags and a gilded mummy mask.
It emerged in January that the exhibition would feature missing missing fragments from an ancient Egyptian treasure - which have been recently reunited with the rest of the remains after 160 years.
The mummy shroud was discovered in a storage facility during preparatory work for a new gallery dedicated to Egyptian treasures, which is due to open at the attraction next year, which will showcase highlights from the 6000-strong collection which is held in the city.
Dr Margaret Maitland, senior curator at the museum, said: "To discover an object of this importance in our collections, and in such good condition, is a curator's dream.
"Before we were able to unfold the textile, tantalising glimpses of colourful painted details suggested that it might be a mummy shroud, but none of us could have imagined the remarkable figure that would greet us when we were finally able to unroll it.
"The shroud is a very rare object in superb condition and is executed in a highly unusual artistic style, suggestive of Roman period Egyptian art, yet still very distinctive. It is extraordinarily rare that we have such an incredible group of objects belonging to a whole ancient Egyptian family in our collections.
"To have been able to expand this group of objects with this new discovery is very exciting."