IDK about UK seems the German products* comply with their laws and cannot flash so they don't..

As far as judging the perception of others seeing those lights, havent there been several univirsity studies on those by now?

I'd research the various research studies to answer your own question.. but you can sit back and just read these few opinions ..

anecdote : I have a hub dynamo and wired head and tail lights *B&M, but I dont live in London or even Portland.

I can use the Pavements, a bike lane and traffic lights on my mere 1/2 mile trip home from the pub



...