I had a load of ‘tossers’ beeping and flashing at me the other day while riding normally…worked out why when I got to work (at 6 PM) and realised I had no lights on!
I did a Bikesafe day and the police man who was leading me was overtaking well out onto the opposite side of the road. I asked him about it and he said it was to increase his view of oncoming traffic and make himself more visible to other road users. Obviously he wasn’t doing this with cars flying towards him.