Sixty-one years after it was stolen from a collectors' convention, a rare Inverted Jenny has been found.

The stamp was one of four Inverted Jennys snatched from an American Philatelic Society display case in 1955.

Inverted Jennys have sold for close to $1m, such is their fame and rarity

Two came to light in the 1970s and 1980s. This one resurfaced after it was submitted to a Spink stamp auction by a British gentleman in his 20s.

The unknown man claimed he had inherited it from his grandfather and knew little of its history.

To add to the intrigue, a letter from 1965 detailing a loan from a stamp dealer to an auctioneer accompanied the stamp.

George Eveleth, the head of Spink's philatelic department, commented: "This is one of the most exciting events in my 38 year career in the stamp auction business." 

The American Philatelic Research Library, which has ties with the American Philatelic Society, has laid claim to the stamp, which is now in a state of legal limbo.

The lender of the four stolen Jennys to the 1955 event, who died in 1980, donated the rights of the stamps to the society.

Just a single sheet of 100 Inverted Jennys were produced. They have been among the most celebrated error stamps since the day the sheet featuring an upside-down biplane rolled off the press in 1918.

Examples can sell for close to $1m in top condition. The fascinating story behind this example could see it beat the $1m mark - should it ever appear for sale.

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