It's very boring having to repeatedly point out that a Glacial Erratic only is evidence of glacial transport to the point where it was naturally deposited. If it has been moved by humans, and there are no records where from, then it adds nothing to the argument. If you don't know where the glacier left it, it don't mean a thing. For erratics the approximate provenancing -- to within a few sq km -- is good enough, exactness would be better but for mapping glacial extent experts agree it is an unrealistic demand, but when there is no evidence as which county or even country it was originally found in then forget about it.
It is much more interesting to learn about tboulder tractors) of Amersfoort, NL
De Kei Van Amersfoort 1661
Schilderij van de Keitrekking, het feestelijk verslepen van de Amersfoortse Kei binnen de stadsmuren in 1661. Anoniem schilderij. https://www.utrechtaltijd.nl/verhalen/de-kei-een-uit-de-hand-gelopen-grap/