Aah, the old Cold War days in West G. when our exercise Air Control Orders required us rotary chaps to fly "not ABOVE 150 feet AGL", to give us a buffer altitude from the jets who were supposed to be not BELOW 250 feet AGL.. Interesting when the HT pylons were up to 300 feet AGL....
The locals were often not too impressed. but I suppose they were more used to it then than today.