I've left the guitar out for a couple of days now and the foul smell is just about gone, more wood smell.
But I opened the case and it's is still strong in there, so definately the case is the problem. That's a relief.
The dealer has the correct size case coming next week. I'll give it a good whiff before I take it home
.
Thanks to all who pointed out the case smell, I can enjoy the guitar more now!
Steve