E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
The well of St. Keyne, Cornwall, has a strange superstition attached to it, which is this: If the bridegroom drinks therefrom before the bride, he will be master of his house; but if the bride gets the first draught, the grey mare will be the better horse. Southey has a ballad on this tradition, and says the man left his wife at the church porch, and ran to the well to get the first draught; but when he returned his wife told him his labour had been in vain, for she had taken with her a bottle of the water to church.