Thanks for your advice. I’ve been spending some time reading about layers but I still can’t seem to get it…
I’ve provided a shot and the .blend to make it easier and hopefully I can wrap my mind around the combination.
The cube in the middle of the room casting the shadow should not be ‘visible’ to the green light. You can see its shadow in the middle of the green spot light, but it should not be there. I set that cube to only the 3rd layer, the white light in the middle to 1st and 3rd, and everything else only on the 1st. The green light is only on the 1st layer and the cube is only on the 3rd layer, so they shouldn’t interact with each other? That seems logical in my mind, but obviously not to Blender:-
