Thank you everyone for your views. He is indeed pooping, eating, playing and generally behaving as a five month old should, and he shows no other signs of distress at all. While I appreciate, we can't know for sure, I do think he is happy here - he is extremely relaxed when he is not tearing the place up and haring around like Rocket Dog! As I speak, he is laying on the table next to the laptop, washing his face after dinner, and occasionally nibbling the corner of my new management book...

I will keep an eye on him though, and make sure he gets lots of reassurance and calm stroking. I suspect I will be woken at 5am for some time to come by him sitting on my head then snuggling up. That's not too bad, it's the dribbling in my ear I don't like!