You never know what could be stashed away in a dusty records office.

Two researchers do know and they made the discovery of a lifetime, thanks to a one-line entry in a catalog from a records office in England, The Washington Post reported.

The entry read “Manuscript copy, on parchment, of the Declaration in Congress of the thirteen United States of America.”

In other words, Emily Sneff and Danielle Allen found a long-forgotten copy of the Declaration of Independence.

Undated handout photo of a parchment manuscript of the US Declaration of Independence, believed to date from the 1780s and found in a records office in Chichester, southern England. Harvard University researchers say they've discovered a second parchment copy of the Declaration of Independence, The Boston Globe reported Friday, April 21, 2017. (West Sussex Record Office Add Mss 8981 via AP).
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Sneff is a researcher with the Declaration Resources Project, an effort to document every known edition of the Declaration of Independence.

She found the entry in August 2015, but wasn't hopeful then that it was the real deal, according to a press release from Harvard.

“I’d found vague descriptions of other copies of the Declaration that turned out to be 19th-century reproductions of the signed parchment in the National Archives, so that was what I was expecting.”

What she wasn’t expecting was the description that it was a manuscript on parchment.

Sneff first contacted the archive and received images of the document.

When the details didn’t match other copies, Sneff realized she had a mystery on her hands.

First she and Allen needed to date the parchment, then find out who commissioned it and why they decided they needed a copy and finally how it ended up in England.

They are using handwriting analysis, parchment preparation study and spelling errors in the signers’ names to try to pinpoint who commissioned it and who wrote it.

At a conference at Yale, Sneff and Allen said they believe it was commissioned by James Wilson of Pennsylvania. Wilson would eventually help write the Constitution and was one of the first justices on the Supreme Court.

They believe the newly discovered document was written about 10 years after the original and shines a light on the political upheaval in the new country.

On what is being called the “Sussex Declaration,” the names of the signers are not in the usual order, grouped by state. They are split. Only one other known version has the names not grouped by state, an engraving from 1836 showing that the 13 states became one group, not a group of independent states.

Click here to read more on Sneff and Allen's investigation.