I have an 18 month old blue merle border collie that we adopted from a farm after he was advertised as a failed sheepdog. When we got him the farmer told us that the working dogs he had never went inside the house and were not treated as pets, therefore living in kennels. We have had him for around 4 months now and all other training has been excellent and due to his intelligent breed, we have had no issues with any training apart from when he does his duty. He goes for 2/3 walks a day, usually lasting an hour each. He is well exercised and regularly poo's when on a walk. However, we do not have a garden, just a large back yard. We take him into the yard and give him access to the full back alley when he is outside but he still defecates inside the house, even after he has just been outside. I have tried numerous techniques but he continues to wait until we are upstairs to go the toilet on the floor. What advice would people give to help resolve this problem?