A ‘JAW-DROPPING’ new study has revealed Stonehenge’s massive ‘altar stone’ – weighing in at a whopping six tonnes and measuring some five metres long – came from Scotland.

For around a century, experts have known the origins of many of the great landmark’s mighty stones, with a number coming from Wales, somehow transported around 125 miles by the prehistoric people who built it.

Now, new research has revealed one of the megaliths is not Welsh, but Scottish.

Analysis of the stone – the largest bluestone on the Wiltshire site – has revealed it was dragged or floated from a north east corner of Scotland – travelling at least 466 miles to south west England, and may even have hailed from the Orkney islands.

“(This) doesn’t just alter what we think about Stonehenge, it alters what we think about the whole of the late Neolithic,” said Rob Ixer, an honorary research fellow at the University College London (UCL) who was involved in the research.

“It completely rewrites the relationships between the Neolithic populations of the whole British Isles,” he told the Guardian.

“The science is beautiful and it’s remarkable, and it’s going to be discussed for decades to come. It is jaw-dropping.”

The alter stone is largely hidden from view, lying flat and semi-buried beneath the Wiltshire land.

A number of other bluestones at Stonehenge are known to have come from the Preseli Hills, in Pembrokeshire, Wales. But the altar stone was an outlier, prompting the new analysis.

The altar stone is buried beneath two fallen sarsen stones and is barely visible to visitors. Picture: Aberystwyth University

The study, published in the Nature journal, involved experts from Curtin University in Perth, Australia; the University of Adelaide; Aberystwyth University; and UCL.

It aimed to find out more about the altar stone through analysing the stone’s chemical composition and age of minerals within it to produce a “fingerprint” to the sandstone.

Nick Pearce, a professor of geography and earth sciences at Aberystwyth and a co-author of the report, said: “With that age fingerprint, you can match it to the same sort of rocks around the UK – and the match for the age fingerprint was a dead ringer for the Orcadian Basin in north-east Scotland. It was completely unexpected to us.”

More work is now planned to try to identify the exact site the stone came from. The experts have narrowed the area down to encompass Orkney; a triangle of land around present-day John o’Groats in Caithness; and a narrow coastal strip stretching south as far as the Moray Firth around Inverness and east to present-day Elgin.

However, the question of how the stone made it’s almost-500 mile journey to Wiltshire is unknown.