A handwritten parchment of the US Declaration of Independence – only the second known to exist – has been found hidden away in a small English city.
The document was discovered in the West Sussex Record Office in Chichester, where staff had been unaware of its significance.
The original Declaration proclaimed the first 13 colonies free from British rule and was signed in Philadelphia on 4 July, 1776 – now America’s Independence Day.
Harvard University researchers Emily Sneff and Danielle Allen made the discovery while compiling records for a database.
It began in August 2015, when they stumbled on a simple one-line entry in the office’s catalogue: "Manuscript copy, on parchment, of the Declaration in Congress of the thirteen United States of America."
They thought it would probably be a 19th century reproduction – but it turned out to be a "big mystery" and far more significant than they imagined.
Now christened the ‘Sussex Declaration’, it measures the same size as the original, 24in by 30in, but has been written horizontally.
It also does away with the state by state signature groupings of the original, and all the names are written by a single clerk.
The researchers discovered it was deposited along with other papers by the so-called "Radical Duke", the Third Duke of Richmond, Charles Lennox.
He earned his nickname because of his support for the Americans during the revolution.
Exactly when and why it came to England is still unknown.
"While the parchment may have moved to the UK in the 1780s or 1790s, when the Third Duke could have received it, it is also possible that it moved to the UK only after 1836," the researchers said.
The mystery could deepen as text appears to have been scraped away at the top of the document.
Hyper-spectral imaging is planned in conjunction with the British Library in the hope of revealing what was written.
Supreme Court Justice James Wilson, one of six people to sign both the US Constitution and the Declaration, is believed to be the most likely person behind the copy.
Professor Allen added: "This one was produced a decade later (than the original) with the signed parchment as its source, as part of the fight between federalists and anti-federalists about whether the new republic was founded on the authority of a single, united sovereign people or on the authority of 13 separate state governments.
"The federalists were making the first argument and this document appears to have been produced to support their case.
"It illuminates the politics of the 1780s in a flash."
(c) Sky News 2017: Rare US Declaration of Independence copy discovered in Sussex