Shrewsbury Herbal Products (SHP) has diversified its business by collaborating with AdibasBuma International, a U.S. company, to export sports gear and equipment, with a focus on football clubs in the United Kingdom. Your objective is to recognize the factors that affect the balance of payments between the U.S. and the U.K., and to explain how these factors could potentially influence the demand for footballs manufactured by AdibasBuma International in the United Kingdom.