After years of discussion this moral dilemma has been solved. The answer was in the bible all along:
?In case you go into the vineyard of your fellowman, you must eat only enough grapes for you to satisfy your soul, but you must not put any into a receptacle of yours." Deuteronomy Ch23v24.
Obviously, in the modern world, the vineyard of your fellow man means the place where we find grapes owned by Tesco and Sainsbury, and we may therefore eat to satisfaction whilst wandering the aisles, but mayeth not stuff 1kg of seedless into oureth handbags.