Round my way, it is rare to see a bicycle with *any* sort of lights, and I have never read anything in the local paper that reported such a cyclist being stopped.
I did once ask someone who had the flashing LEDs fitted how long the batteries last. He reckoned that one set would last all winter, using them every workday. Very economical and environmentally friendly!
These days, if you don't attract the attention of a Gatso or radar gun, and you don't talk on a mobile phone, the police probably won't notice you.
Jim