Orion and a puzzle (solved)

On my way to take photos of the lights last night I had a go at some stars. It was nice to get some colour in Betelgeuse. I was puzzled by the reddish glow in the bottom right of the shot. I could not work out why there would be a a glow to the south. There is about ten miles of open country without habitation until you get to Loch Torridon, the habitations around there are few and far between and there are some big hills in the way. Then I remembered. for one or two of the shots I had forgotten to turn off my head torch which was set to red.

I can't be sure it was the cause but I am fairly confident and can't think of anything else it could be.

Dave