Stone with 1,600-year-old Irish inscription found in English garden

A man in England weeding his garden has made a once-in-a-lifetime discovery: a stone inscribed with a 1,600-year-old message in a rare Irish alphabet.

At first glance, the inscription looks like a series of vertical lines cut into the chocolate-bar-size stone. But these lines are actually an inscription in ogham, an alphabet used to write the early Irish language after the fourth century and Old Irish from the sixth to the ninth centuries. Its discovery has baffled archaeologists, who can't explain how it came to be in the central English city of Coventry.

Ideas include that it might have been a commemorative object, something carried by Irish Christian monks on a mission to convert the pagan Mercians of the area, or a way of introducing a traveling Irish tradesman to others. 

"There's a lot of possibilities as to why it came over," Teresa Gilmore, an archaeologist at the Birmingham Museums Trust, told Live Science. "This is one of the things about some of the amazing finds that turn up — they often create more questions than answers."

Gilmore is a finds liaison officer for the British Museum's Portable Antiquities Scheme, which learned of the inscribed stone in 2020.

Related: Rare medieval script discovered on stone carved by Scotland's 'Painted People'

Geography teacher Graham Senior found the stone while he was weeding a flowerbed in his garden in Coventry during the COVID lockdown in 2020. "It caught my eye as I was clearing an overgrown part of the garden," he said in a statement. "At first, I thought it was some kind of calendar. Finding out later it was an ogham stone and over 1,600 years old was incredible."