That must have been great fun. How did you stop the helper? Stopping cats from doing things, as I think most members know, is not the easiest thing in the world to do.
On top of that, I have a feeling that scratching has some sort of significance for cats. When I had Zenobi I wanted to encourage her to scratch at a sheet of plywood that a previous stray had used for that purpose. The method I tried was to demonstrate by scratching on it with my fingers. Zenobi, who was sitting on the open back stairs leading up to the sundeck, went crazy. When I put my hand out to her as I asked what was up, I was subjected to frantic lovebites. I ran indoors for five minutes.
So I'm wondering if Prince got some sort of message from your scratching.