A copy of the United States Declaration of Independence discovered in an attic in Scotland has sold at auction for more than £3 million.

The signer’s copy is a representation of the original 1776 document that declared the independence of Britain’s 13 American colonies.

It was presented to Charles Carroll of Carrollton, a Founding Father who was one of the signers of the Declaration and later a US senator.

He gave it to his grandson-in-law John MacTavish, a Scottish-Canadian diplomat who lived between 1787 and 1852, and it descended in the Scottish family.

It was discovered in the attic of a Scottish ancestral home by Edinburgh-based auctioneers Lyon & Turnbull, who passed it to their sister auction house Freeman’s in the US.

The rare document sold on July 1 – three days before the July 4 Independence Day holiday in the US – for $4,420,000 (£3,210,000), the second highest ever paid at auction for a copy of the Declaration of Independence.

The signer's copy of the Declaration of Independence was discovered for the first time in nearly 180 years

Credit: Lyon & Turnbull/PA Wire

Cathy Marsden, who works at Lyon & Turnbull, discovered the document, which was unaccounted for for nearly 180 years.

She said: “I was looking through a pile of papers which had been brought down from the attic, amongst which was a folded-up, vellum, document. Opening it up, I could see was a copy of the Declaration of Independence.

“When I got back to the office and started doing some research, I became really excited as its significance became clearer.

“After extensive research, we confirmed it was indeed one of the 201 copies made by William Stone, of which only 48 of them are known to still exist. Being able to identify to whom the copy belonged made it even more exciting and rare.”

Paul Roberts, vice-chairman of Lyon & Turnbull and president of Freeman’s in Philadelphia, said: “This was a great effort from both teams on both sides of the Atlantic, a very proud moment for me personally – an international team working in perfect harmony to achieve a wonderful result on behalf of an extremely appreciative and supportive client.

“When Cathy Marsden first showed me this document on Christmas Eve, I knew it was interesting, but today’s outcome – achieving $4,420,000 on the eve of Independence Day weekend nearly 4,000 miles away – is extraordinary.”

The seller of the document has chosen to remain anonymous.