In the 1970s the balance of payments was considered an important metric, but in the era of a floating currency much less so. If the balance of payments is negative, that means that British people have more shiny things to but, and they don't have to make them. If you want the balance of payments to be positive, stop British people buying stuff. But you won't be popular. The US runs a massive deficit on its balance of payments and has since the 1970s. It hasn't impacted upon the value of the dollar.