I always taught and demonstrated practice pans on 121.5 to my students (I also insisted that they declared themselves as "LOST" not "temporarily uncertain of position" what a mouthful and frankly a load of b****x). Shortly after going over the procedure with a colleague's student, I had the pleasure of hearing that student using it for real on a solo nav. As you'd expect D&D handled it with utmost professionalism and I listened in while teaching practice autorotations to my student. Also listening in was the local police unit who I could see hovering nearby and offered his assistance. Eventually the lost pilot reported visual with the destination. At this point the police unit piped up, reporting that he thought he was visual with the lost aircraft, and that he couldn't be visual - the airfield was behind him. D&D asked the lost pilot to confirm he was visual with the airfield, which he did and requested change to XXXX. I could not resist telling the police pilot (on 121.5) that I believed he was looking at me. I did however restrain from asking why he thought that a lost pilot would be doing practice autorotations.