She has agreed to baby sit for a few hours while I go with him to see his mum in hospital (she has had a knee replacement) as he has told her he would bring me along with him.
Mum wants to come round to my house rather than have boys overnight, so I said that I would probably invite him in when we get back, and would she be prepared to say hello to him.
She was very "Hmmm" at first, but has now said ok, so long as I don't tell anyone. She is obviously worried about dad or ex H finding out she has met him.
I guess this is slight progress though.