Totally agree. Guard Police need to shut up. Too many times they blot out real (or normally practice) transmissions. I think the main trouble is that from an airliner at FL390 or higher these UK calls are heard for 250 miles or so inside mainland Europe - Germans (as well as US) seem to try and Police 121.5 quite regularly possibly not hearing the UK ground controller and only hearing the aircraft in real or practice trouble.
My gut feel says all practice calls (not the one in question here) should be on an alternate freq. We are supposed to monitor 121.5, most times near UK airspace it is totally impracticable due the number of practice calls (and no doubt hence the guard police response). Personally I just de-select 121.5 so I can hear Box 1. Not the real solution
