The Brexit debate has given rise to many bewildered discussions about the apparent difficulties of negotiating trade agreements.  After all, as at least one commentator said, if we can put a man on the moon, surely the UK can negotiate a few trade agreements?  Of course.  Compared to putting a person on the moon, many things seem easy.  But the complexity of negotiating trade is not to be underestimated either.  To illustrate why this is so challenging, just consider the following example of orange juice.