Thanks guys. As for stop digging thats not really an option as im at the end.

Each spade full was placed on a 6x2foot plyboard and manually "sifted" moving the soil/spoil by hand across it removing anything even remotely organic of any size let alone a 2-3cm piece.

Not naive enough to think I have it all but surely a small piece regrowing will die off quicker by treating *that* with chemicals and (I love this idea) preventing photosynthesis than some of the some one foot long and two inches thick roots ive pulled up/removed.

Still left with the driveway but i feel i will wait for it to grow and attack it then.