A previously unknown, 312-year-old map of Canada that was found rolled up and covered in dust in the attic of a Scottish estate sold Monday at an auction in Britain for $318,000 nearly triple the expected high-end price of about $125,000.

There was a fierce bidding war for the one-of-a-kind artifact between potential buyers in Canada and Britain, a director of the Somerset-based auction house Lawrence Fine Art told Postmedia News.

For now, said Lawrence official Richard Kay, the identity of the successful bidder is not being revealed.

The contest began "with a spoken bid from somebody on the phone of 60,000 pounds, and it climbed pretty quickly," Kay said moments after the hammer came down on the cartographic treasure.

"Manuscript maps don't come on the auction market very often, Kay" noted. "And manuscript maps that relate to Canada and North America at the end of the 17th century are very rare indeed."

The large, hand-drawn depiction of New France, "Nova Britania" and other North American colonies was created in 1699 by English map-maker John Thornton, one of Europes leading cartographers of the late 17th and early 18th centuries.

Thorntons few surviving original maps are coveted possessions in museums and private collections around the world, including one from 1709 completed a year after Thorntons death by his son, Samuel held in the Hudsons Bay Company archives.

The 1699 map sold Monday features extensive details about fishing areas throughout Eastern Canada, but also captured the known shape of the continent as far west as Manitoba.

"The map also had the benefit of being signed, which is unusual and a huge advantage," said Kay.

"We know it was by this map-maker John Thornton," Kay said, adding that research by Lawrence manuscript specialists and archivists from the British Library confirmed that it is an "entirely genuine example" of Thorntons work.

The 68-by-80-centimetre vellum map, drawn on sheepskin to help ensure its preservation, is described as meticulously coloured and remarkably well preserved.

Thought to have been commissioned solely for the use of a commercial client in Britain who was interested in identifying key North American fishing grounds, the map includes labels for "Labradore, New Scotland" (Nova Scotia) and the island of "New Found Land," as well as the southern part of Baffin Island and northern edge of the fledgling American colonies of New England.

Curators from the auction firm discovered the map while evaluating items for an estate sale following the death last year of the owner of a country home in Aberdeenshire.

The map had apparently been stored undetected on a shelf in the Scottish house "beside some water tanks" for generations, Lawrence Fine Art said in a December statement announcing the sale. "But its potential significance was recognized immediately."

Two maps by Thornton, who lived from 1641 to 1708, are highlighted in B.C. author Derek Hayes' definitive Historical Atlas of Canada. Hayes notes that John and Samuel Thornton played a key role in charting navigation routes and coastal forts for the Hudson's Bay Company, which received its royal charter in 1670 and was soon battling French rivals for control of the North American fur trade.

Other maps were produced for the company by the Thorntons," Hayes writes, but few have survived."

He notes that the Thornton map made for the firm in 1709 which closely resembles the map found in Scotland is the only one now in the Hudson's Bay Company archives."

The map sold Monday included a trademark Thornton compass rose featuring blue, green and red points of direction.

Map specialists at the British Library have suggested that the map might have been a special commission for a patron on account of the considerable detail given to small settlements on the Newfoundland coast, implying an interest in the local fishing business," the auction house had stated ahead of the sale. "Its surprising appearance in a Scottish country house is explained by the business interests of the late vendor's father, Harold Fortington, who had links with Canada and North America before the Second World War."