The work is especially exciting because most stones of its kind have been moved from their original positions.

This makes it difficult to understand how they related to the landscape around them and the messages they were intended to give out.

The St Orland's stone stands on a rise in marshy ground on farmland near Glamis, overlooking what might once have been the farthest extent of the Loch of Forfar.

Kirsty Owen, Historic Scotland cultural resources advisor for central Scotland, said: "This is a fascinating project and will help us understand more about the stone.

"It dates from a time when Pictish kings were encouraging their people to convert to Christianity.

"A stone like this, carved with a cross on one side and images of men and fabulous animals on the other, would have sent out a powerful message about the increasingly close relationship between Pictish kingship and Christianity.

"Its location on a high spot overlooking water meant it could have been seen from a great distance.

"The stone is of particular interest because it has Scotland's only known Pictish carving of a boat, offering valuable evidence for what craft of the time may have looked like."

The archaeologists hope to be able to confirm that the stone is in its original position by revealing evidence of the socket stone which anchored it in the ground.

So far the prospects look positive as there does seem to be archaeology around the base of the cross.

The 2.4m tall St Orland's stone is an impressive monument but centuries of exposure to the harsh Scottish climate has caused cracking and has eroded some of the carving.

At some point the stone was broken in two - how this happened is unknown - and is held together with metal braces and part of the back was also defaced with the carving of a deep but irregular inset panel.

Historic Scotland is carrying out the project to help inform its strategy for protecting the stone and for its future presentation it to the public.

Evidence of prehistoric cist burials nearby may mean that this was a place which had spiritual significance over a long period of time.

Ornate cross slabs of its type were created from the early 8th century throughout eastern Scotland but are a particular feature of Angus, Perthshire and Fife.