This was a good link for info on prehistoric Wells:
http://www1.somerset.gov.uk/archives/hes/downloads/Somerset_EUS_Wells.pdf
There were some useful maps, too.
Further 'Googling' found that there was a limestone quarry on Tor Hill that closed in the 1950s, called [Finlay Breton] Torhill Quarry so maybe it was found near there? It is now an industrial estate.
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