A British historian who discovered a Magna Carta copy was a genuine manuscript has shared his theory on why the document was misidentified.
Harvard Law Library bought a version of the royal charter at auction for just $27.50 in 1946, the equivalent of around $450 (£328) today.
The vellum document was described as a "copy made in 1327... somewhat rubbed and damp-stained" - but two historians last month discovered it was actually a rare original worth millions of pounds.
The document was just one of seven versions of Magna Carta to survive from King Edward I's 1300 issue of the charter.
Professor David Carpenter, who made the discovery with Professor Nicholas Vincent, believes "post-war chaos" is to blame for the confusion.
Speaking at a meeting of the Pipe Roll Society at The National Archives in London, he said: "This was just after the war, there was still a measure of chaos, someone has misread the date on it.
"This is most likely how it happened."
Following the discovery, Prof Vincent traced the history of the document prior to Harvard buying it.
His research suggests that after it was issued by King Edward I to the former parliamentary borough of Appleby, it fell into the hands of a family before being passed to slavery abolitionist Thomas Clarkson.
Via his estate, it ended up in the hands of Forster Maynard, a World War One flying ace, who sold it to London book dealers Sweet & Maxwell for £42, which then sold it to Harvard.
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Prof Carpenter, a medieval historian at King's College London, immediately realised the 'copy' looked a lot like the real Magna Carta when he spotted it in Harvard's online catalogue.
"I immediately sent the image to my colleague Nicholas Vincent asking him 'Is this what I think it is?'," he said.
Speaking at the same meeting, Prof Vincent said: "I told him immediately, you know what that is!"
Magna Carta was originally established in 1215 under King John and outlined the rights of ordinary people under common law for the first time.
It has since formed the basis of constitutions worldwide.
(c) Sky News 2025: Historian blames post-war 'chaos' for Harvard Magna Carta 'copy' confusion
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