The logical extension of Colin Irwin's argument, it seems to me, is that there is no difference between trad or written by. Therefore what is the point of having two categories? Best Song full stop! It's the BBC/Smooth Ops who set up the categories so if they've either got to police it properly or scrap the difference and go for only one category.

I wonder also if a song has been nominated in both categories and been hushed up?