It's been 10 days now and no incidents in the guest bedroom.
We started using potting soil instead of litter and what do you know - straight in and does the business! He misses the box sometimes but he is in there, that is the most important thing!
So now we are mixing litter and soil. Soil is just too difficult to keep clean, it smells more and is much more expensive!!!
Andy and I are so much more relaxed now and there is no more talk of the pound! I don't think he'll ever use just litter though. We have two litter boxes - one with the soil/litter mix and the other one just litter and he won't go near that one so we're going to add a little soil and see if that makes a difference!!!!
Thanks to everyone who has been giving us advice over the last few months!!