I find this quite intriguing; it's well known that market crosses - popular constructions - were placed so that those who came to barter had a point of focus. Indeed, the type of cross we have at bedlington - quite rare now, as it happens - is known as a 'nail'. One explanation for the expression 'to pay on the nail' is the association with bartering and dealing at them in markets. This information was told to me by my grandfather when I was about eight, when visiting bedlington to see relatives. When it was built may be something of a mystery, but I don't believe why should be.