John Sheriff, an investigator with the Royal Commission on the Ancient and Historic Monuments of Scotland, said it was impossible to date the stone precisely but it is very likely to be neolithic or Bronze Age, and could "easily" be 4, 000 years old.

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But the country's Nuclear Regulation Authority, which was created in response to the Fukushima disaster, has said meeting this date is "impossible" as new safety regulations won't be released until December.

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When he talked to British Prime Minister Tony Blair after the decision on a date had been announced he denounced it as "impossible to accept".

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