Thanks for your insight Paul.
I find it quite interesting how stringers advertise. Stick something that looks official on the poster, and people think, well, that it's something official. 99% wouldn't have a clue about any of the organisations, or what they represent.
Perhaps I should have a business card made up with 'DFTT Certified' on it, and see if anyone asks what it stands for. (Dags From Talk Tennis, for those of you that did.)
My String Journey: http://tt.tennis-warehouse.com/showthread.php?t=362403