Copyrighted artwork by Sydney Harris Inc. Published in Wade, Michael. (2016). From Ockham's razor to Rube Goldberg: Don't rely on forensic age-dating miracles. Environmental Forensics. 17. 131-135. 10.1080/15275922.2016.1163754.
Oh, please. Assuming in step two that a rock was found "nearby" without evidence means that the convoluted reasoning that depends on the provenance of the rock is meaningless.
Occam's razor rules that a rock found in a jumble of other rocks transported to the area by humans is more likely to be also transported there by humans than by an Ice Fairy.
There are no glacial erratics, moraines, debris, drumlins, drifts or eskers recorded as having been found naturally on Salisbury Plain. There are lots of large stones that humans have moved. Some of the large stones may have been glacial erratics or debris but they were then transported by humans. It is where they were moved from that needs to be shown not where they ended up if you want to demonstrate a glacial theory.