John,I'm not 100% sure but I think you will find this is an orange light? This would only come on if there was a problem down below,eg taking in water,which would trigger the orange light to start flashing.This is done because for instance the boat may be out on her moorings,and if the crew saw the orange light flashing they would know there was something wrong and would have to investigate.This is what happens on the Tamar,so would assume it to be the case for most boats?
Mick F