Well thank you all for your words of wisdom. I am new to Gransnet and am amazed at the response to my cry for help.
I should explain a little more about the behaviour of my GS who is a delightful little boy at times. He is very bright and was counting to 20 when he was just two. He is very strong willed to the point of calling everyones's bluff what ever happens. He goes to nursery and enjoys his time there, however his key worker sees him as very determined to get his own way and has to stay with him at time out. He is a very bad sleeper and can be up 2 or 3 times a night and is up at 5.30 every morning. Consequently his mother is exhausted most of the time - she is not an inept parent foxie and I would describe my GS's behaviour as very unmanageable at the times of his meltdown. Yesterday, he behaved badly at the dinner table, picking up food with his fingers, jumping up and down on the chairs, throwing himself at his mother and more. We tried everything we could to make him sit even for a few minutes to eat his food but he refused so after 3 warnings we put his food in the garden room next to the kitchen, this is when he started to scream arch his back run around the garden just being a pain. This went on for about half an hour so we left him to work it out of himself which didn't work. Eventually his mother put him in the car and drove him round for 20 minutes hoping he would fall asleep, he didn't but came back more subdued after screaming for the whole 20 mins.
this may be a stage he's going through and we may not be perfect parents or grandparents but we are all feeling pretty helpless to know what to do. I have had three children and have never experienced this and my daughter is so exhausted I worry she is heading for a breakdown.