Hugh - "Standby for departure" isn't such a bad thing. As an enroute controller, I go looking for an aircraft 10 mins after they call taxiing. If it has been a while, some pilots will give us "Centre, ABC, airborne YXXX, standby for departure" so we don't bug them for the departure.
RENURPP:
Its like all these crazy readbacks that some ATC's want, particularly military, and some pilots simply do. Because they don't know any better
Let me guess, "Cleared Visual Approach". Are you ever going to let that one go????
Cheers all,
NFR.