Agree about the "nothing new" comment. And I certainly didn't mean to imply that I was the first to do it. I had the idea for such a layout long before I built it, but had never seen a revolving layout before I built mine. Still, I found out later that they had been built and was not surprised by that.
Mine was built on an old shop display turntable that had a mains outlet fitted to the turntable. So easy to power the layout through that. It was this that gave me the idea to build a layout on top. Just took me around 6 years to finally start. The layout was finished in a few weeks. The train is powered by a radio-control power pack. Just a standard 12v DC model railway controller. Just it has a hand-held radio controller to operate it.