055166k. I'm not sure of your background but all you disagree with was employed many, many, many times at Heathrow and, I know for sure, other airfields too. Nobody was trying to put the fear of God into our "customers" - urrgghh, I HATE that term but realise that it is beloved of modern managers. VFR light aircraft were not "customers"; we gave them a damned good service for free. However, we were required to report any zone infringements and always tracked the aircraft in an attempt to identify it. This was usually done by the Approach Supervisor; maybe the SVFR Director if he wasn't busy. Phone calls to other units were dealt with similarly.
<<I also question on what authority you can order another unit to issue a squawk instruction to a pilot at a possible crucial time in his/her flight, particularly in a circuit pattern when workload could be high and that instruction may compromise the safe conduct of the aircraft....landing checks for one example....traffic lookout for another......possibly a student.....BIG liability to take on!! To say nothing of the distraction to your primary task.>>
The responsibility for passing the instruction rested with the controller at the other airfield and he could have refused. It caused NO distraction to anyone's primary task. Everything worked very smoothly.
About 50% of pilots who infringed and then rang us would apologise and admit their error. Unless their actions had been reckless they were told to please be careful and no action was taken. If a serious infringement occurred requiring us to delay Heathrow traffic, or if the pilot was adamant that he couldn't possibly be wrong, then we tended to throw books around.