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Morace Park was footling around on eBay looking for antiques when he stumbled on an item that was listed casually as an "old film" – and even then he was really more interested in the tin it was in.

"It had a lovely look to it," said Park. But the contents of the battered container, which he bought for the princely sum of £3.20, have turned out to be a previously unknown film by Charlie Chaplin.

Park – who, when he is not buying and selling antiques as a hobby, runs a company that develops products with inventors – bought the film "from someone else who deals in bits and bobs". When his parcel arrived, he didn't even bother to open it for a while. But when he did, he unfurled a little of the film and saw the title: Charlie Chaplin in Zepped. "I Googled it," he said, "and then my interest was pricked. I couldn't find any sign of it on the internet."

Park, from Essex, enlisted the help of a neighbour, John Dyer, the former head of education for the British Board