Majormellons is the winner. SDQ came very close.
Around about 1990 a very large boat sailed in and drew up against the wall. Ancours out. Gangplank down. Arrived to stay. It was of course called "Conwy."
It then opened as a restaurant. Didnt take long for the Council to say Hey, business, rates. So the bill arrived. The owner manager Captain, whatever said "If I've going to pay rates, then I want rubbish collected --- and I'm sticking a postbox by the gangplank, and mail can then come to me." So that is how the address came into use. mike