I've seen a video with him and his horse Sheik that seems to show the bond that you're talking about. Sheik was all tacked up and with a new rider on him but he would still follow his trainer everywhere. Sheik was giving pony rides there and his trainer thought that it will be a good idea to not use a lead rope on him. The horse was following his trainer like a dog in a complete new environment.
But I don't know if the horse will follow his trainer in a field without being tacked up (in order to feel that he's at work). I didn't see this pair at work to understand their relation yet.