is it a lawful command to say "ride on the pavement or I'll nick you"?
My understanding is that even if e.g. a shared use path is available, you are under no obligation to use it. There is one such near me that I'm loath to use because it's full of slow cyclists who aren't aware of speed differential, pedestrians with earbuds, crosses several side roads that vehicles tear in and out of, and eventually departs from my direction of travel. As a reasonably fast road cyclist it's likely create more problems than it solves, whilct I'm not holding up traffic any more than a tractor would.