Stunned librarians stumbled across a 3,500-year-old tool “hiding away in a store room” while they were tidying up.

The Tutankhamen-era artefact, which was originally found in an Egyptian tomb, was rediscovered by staff at The Kent Museum and Library of Freemasonry in Canterbury.

The site already houses a wealth of historical treasures and books, but now it has another - recovered from its own back room.

Chairman of the trustees Richard Wingett came across the ancient wooden maul - a tool used for creating cave writings and pictures - while preparing the museum to reopen to the public.

He says the rediscovery of the item was both delightful and worrying.

“It caught my eye as I was walking past, and I pointed at it and said ‘what is that?’,” said Mr Wingett.

“I felt quite elated that we found something so old and probably very rare, but at the same time a little bit concerned that we’ve had this thing kicking about in the background for years that nobody knew existed.

“It was in a display case that was covered in dust and had a sign saying that it was found in a tomb in Saqqara near Thebes in Egypt.”

After the revelation, Mr Wingett contacted Egyptian experts at the British Museum, who confirmed the artefact’s authenticity.

“It is absolutely genuine and 3,000 to 3,500 years old,” said Marcel Marée, assistant keeper at the British Museum’s Department of Egypt and Sudan.

“The mallet would have been used by a stonemason or sculptor in combination with a copper-alloy chisel.

“The old label is confusing, because Sakkara (Saqqara) is not ‘near’ Thebes (modern-day Luxor); the two sites are almost 500 km apart.

“My hunch is the mallet comes from Luxor rather than Saqqara, just like the majority of parallels I know.”

With the Canterbury museum this year celebrating its 90th anniversary, Mr Wingett hopes the artefact will bring an influx of new visitors.

The centre in St Peter’s Place houses a collection of rare and historical items including a sword from the Crusades, a 1588 Geneva Bible and about 12,000 centuries-old books on the history of Kent.

Museum bosses intend to open the collection of books as a public research centre for the first time this year.

The newly rediscovered maul is currently off display as a security case is being sought to protect it from any potential damage while on show.

A similar maul was bought at a car boot sale in Northumberland for £3 in 2014.

Historians later valued it at closer to £4,000.