A researcher in Wiltshire, U.K. has uncovered the original source of the image on the cover of the 1971 record, Led Zeppelin IV.
The image was found in an album of photographs taken by Ernest Howard Farmer.
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The man Farmer photographed has also been identified as Lot Long (1823–93), who was a widower residing in a small cottage in Shaftesbury Road, Mere, when the image was taken.
As someone who has owned this album since about 5 years after it came out, I don't think I would have gotten any further than "That looks somewhat familiar."