This is a bit vague. Perhaps the stone isn't here any more. And even if it were, it's surely a Disputed Antiquity. Apologies. I can see it marked on a map from 1890. The spring itself is still at the side of the Watergates Lonning track.
On the common, to the east of that village [Blencogo], not far from Ware-Brig (i.e. Waver Bridge) near a pretty large rock of granite, called St. Cuthbert's Stane, is a fine copious spring of remarkably pure and sweet water; which (probably, from its having anciently been dedicated to the same St. Cuthbert) is called Helly-Well, i.e. Haly or Holy-Well. It formerly was the custom for the youth of all the neighbouring villages to assemble at this well, early in the afternoon of the second Sunday in May; and there to join in a variety of rural sports. It ws the Village Wake; and took place here, it is possible, when the keeping of wakes and fairs in the church-yard was discontinued. And it differed from the wakes of later times, chiefly in this, that though it was a meeting entirely devoted to festivity and mirth, no strong drink of any kind was ever seen there; nor any thing ever drank, but the beverage furnished by the naiad of the place. A curate of the parish, about twenty years ago, on the idea, that it was a profanation of the sabbath, saw fit to set his face against it; and having, deservedly, great influence in the parish, the meetings at Helly-Well have ever since been discontinued. We honour his zeal; but there are many principles and practices in the place, which we cannot but be sorry, he was not so successful in reforming, as he was in attacking this ancient, if not innocent custom; which would have been thought no abuse of the sabbath in most of the other countries of Christendom.