Well I went to see him again today and he is much more trusting of us. We played with him with some string and gave him some scratches behind his ear - he has such a cute purr. My boss had left some dry food but he hasn't touched it - so i went to the local shop and they had some of those whiskas pouches. Wouldn't be my choice for my cats, but compared to the scraps he was getting living under the deck, it must have been a feast for him - he ate 2 whole pouches and half a carton of whiskas kitten milk.
I called my boss and told him how friendly the kitten is getting already - he is so mad that animal control said that he was too feral to keep and were going to euthanise him. I have spent less than 5 hours with him and he will already take a treat from my hand!
I still can't get the mother to come out from hiding while we are there, but she drank he cat milk and ate last night and is using the litter tray so she seems OK. I just hope the trucks from the warehouse don't freak them both out on tuesday morning when we are all back at work!