I'm another one for the "Clear Prop" call. If anyone I'm flying with doesn't like it... tough! I'd rather have an upset passenger than a dead pedestrian.
I spent about nine months in California, flying, where aviation really is open to anyone.. a little too open if you ask me. There was absolutely nothing to stop Joe Public wandering onto the GA ramp. I don't want to dumb down Joe Public, but they don't seem to realise that a five foot disc of spinning metal can do considerable damage. A rather loud "Clear Prop" seems to get their attention, not least because it has a "quaint" British accent
Incidentally calling "Clear Prop" is fine if you have a prop... but what do you call if you have a turbine of some description? It can be quite hazardous at both ends of a Jet Provost, for example.
Keep it safe
BlipOnTheRadar