Thanks for the insight Snodderly and Cat. It is very interesting and I am learning all the time.
Interestingly I think his childhood issues come from being 9-13 years when he cared for his mother before she died and had a poor relationship with his father!
He is also favouring one child D19 who he lavishes more time and money on. He also communicates constantly with her but not so much with the others. Luckily the other 3 haven't caught on yet but I am sure they will in time!
One of the things my H used to say before he left was that the children always had more than him and that I would let them get away with things, particularly one son 16. He now has a difficult relationship with this son since he has gone to live with OW.