His Grace,the late Duke of Portland has something to say:
"The Grey Hen's Well does not commemorate my famous horse St. Simon."
The Grey Hen's Well has gathered another myth which seems to be remarkably widespread, claiming that the Duke of Portland placed the stone at the Grey Hen's Well to commemorate his famous horse St. Simon.
Joy Corley of the Welbeck Estate, Berriedale has this to say:
"According to two previous factors, both knowledgeable in the history of the Welbeck Estate, the Duke of Portland's famous horse St Simon. had no affiliation whatsoever with the stone marking the Grey Hen's Well. Nor has any other horse.
The Duke was famous for erecting stones and had a great sense of humour so the story of the old lady spying on her daughter would have appealed to him.
Elderly locals currently in the Berriedale area also have never heard of the legend of the horse."
Sources: Duke of Portland caricature aka : Cavendish-Bentinck, Vanity Fair, 1882-06-03. Wikipedia
Joy Corley personal communication 2009