Update. First of all, my granddaughter loved her present today and drew me a picture with a message to say she loves and misses us. This is how important this subject is in her whole future life.
My son listened very closely. He seemed not to have thought about the fact that as Bibbity said his ex-wife could get the Absolute then at any time after tell him to f* off. At no stage during the pre-court mediation was any access arrangement even mentioned. Rather than go to court for an order he is initially going to contact his ex in a conciliatory way and try to become more involved with his children, whilst at the same time trying to get his partner to agree that his daughter should also, at least for a short while, be able to come to his flat. Their relationship is volatile but it may all be tangled up in this mess.
I also asked him to write to his elder daughter, whether or not she responded at all or with hostility, commenting on her very good school performance and any other matters. Everything to be along the lines of building bridges.
I read correspondence going back to 2016 from his now ex-wife, and I can see that although she was very difficult, she was fighting to keep him involved with his children. I asked him to write to her in a spirit of recognition of what she has done in raising them, under duress, and basically butter her up but not insincerely, just try to get everyone, ex, daughters, partner, building bridges. I also noticed a message instructing us, the grandparents, not to have any contact ever again with her or her daughters, so it's all as bitter as could be, but time does ease things.
I told him he has no rights but neither does she in banning contact with our side of the family - there are, after all, aunts, uncles and cousins as well all left out - and if she did implement the threat to stop him taking his daughter out then it would be a court access agreement. With him - not us.
Hope must live on and fundamentally we are fighting for a young girl's wellbeing.
So, very receptive.