Apologies for being flippant. You are correct in your last point that's for sure.
So, help me because I am still confused, when I overtake you and you flash you are telling me it is safe to pull into the left hand lane?
If that is the case then the car overtaking you that i haven't seen is in the middle lane, so the safest thing for me to do is pull into the left hand lane, which I would do whether you flashed me or not, unless I was overtaking another car or lorry. So are you flashing me to say it's okay to pull in or are you flashing me to remind me to pull in to avoid the car that I poss