A bookseller doing research in Britain's National Archive stumbled across an original copy of the Declaration of Independence, one of only 26 known to still exist and the third copy in the National Archive; 200 were originally made on July 4th, 1776.
It was mixed in with 18th century U.S. colonial correspondences which the British had intercepted, but how this occurred isn't known. One theory is that the Royal Navy captured it while fighting in the American Revolutionary War.
The last copy was found in 1989 and sold for £4.94 million. A spokesman said: "It is likely that only around 200 of these were ever printed, so uncovering a new one nearly 250 years later is extremely rare, especially one in such good condition."