Thanks PKD. I finished the gridfill quite quickly this morning after splitting up 1D. Don't give up now, Simon :
Everything goes in normally apart from 4 entries which get split up (2 have already been given on here), 4 entries where OUT stays out, and 4 entries where ON gets reversed.
Absolutely agree with other comments, I still don't see the source (perhaps Carl someone ?) but can't be bothered. More work to do outside...