Harassment is never appropriate, of course not. But calling 'out of hours' is normal in certain jobs where there's an expectation or a need for swift resolution. Thanks for saying I sound ridiculous though, always a pleasure.
As someone who has has spent my entire career in the jobs you are referring to, where there is an expectation that the work will be done whatever the hours (getting necessary orders from the High Court over the telephone from at 3am, for example) I stand by what I have said. If there was something that the staff member should have been doing that night, then calling them every 10 minutes to check up on it is still micromanagement that can easily cross over into the bounds of harassment.
And, this is also ignoring what the staff member in question actually said:
On another occasion, when Meghan felt she had been let down over an issue that was worrying her, she rang repeatedly when the staffer was out for dinner on a Friday night. “Every ten minutes, I had to go outside to be screamed at by her and Harry. It was, ‘I can’t believe you’ve done this. You’ve let me down. What were you thinking?’ It went on for a couple of hours.” The calls started again the next morning and continued “for days”, the staffer said. “You could not escape them. There were no lines or boundaries – it was last thing at night, first thing in the morning.”
So they weren’t ringing because she needed to do work, they were ringing to scream at her for something she had already done that they were unhappy with.