From plaque attached to the railings;
The Kempock Stone
A Bronze Age Standing Stone, dating from about 2000 B.C.
This is the famous ‘Lang Stane’ of Gourock, more familiarly spoken of as ‘Granny Kempock’ … It is supposed that the Kempock Stane marks the site in Druid times of an altar to Baal …
However that may be, the Kempock Stane was for many centuries an object of superstitious awe and reverence … Marriages in the District were not regarded as lucky unless the wedded pair passed round the ‘lang stane’ and obtained in this way Granny Kempock’s blessing …
It was chiefly in connection with the winds and the sea that the Kempock Stane was regarded with superstitious dread … sailors and fishermen were wont to take a basketful of sand from the shore and walk seven times round Granny Kempock, chanting a weird song to insure for themselves a safe and proseperous voyage.
quote from Rev. D. Macrae, “Notes about Gourock”, 1880