I also have seen this on various post war Norton pictures and actually purchased one of those back in the late 70ties in a scrapyard here in Holland.
It appears that after the end of the hostilities, the safety of riders was more important than the black out function.
Many Canadian machines were left in Holland after the war and used by the Dutch army. I am fairly sure the headlamp came from one of those as the scrapyard used to buy surplus military motorcycles for many years. It even had original Vokes Aircleaners lying around. Unfortunately, I had no clue then that they even existed.