Girls, girls, girls,
Alex and CAP56, you are both right. You will see from my previous post that I tried to explain BFL in terms of selecting V1 to balance the ASDR & AGDR........this is the American way of doing things.
I had to refer back to my books(The Aircraft Performance Requirements Manual by RV Davies). According to this book the Brits do say that a Balanced Field exists when ASDA = AGDA.
This was was a revelation to me! I have to now sit down and rethink a subject I thought I understood. I am not sure why they did it this way, but I am sure we can get to the bottom of it.
KTK