Tops of the rails scrubbed and polished and time for a quick check. Bzzzzzzt! Hmmmm small short. Well big short really as proportionally this is pretty simple. The controller was moved and the board flipped over, the problem was quickly traced to a point and a wandering wire on the switch. A modicum of bending sorted it out and all was well. Only I could short out a two-wire feed inglenook.
Some initial scenery profiles are in at the near end. It looks huge here, but it's only 3'7" x 10".