Since seeing the thread title, I've been thinking about why "'H' as I call him " is so irritating.
And what I've come up with is:
A lot of us call our partners by pet names or diminutives. So, imagine if Mr LaM was called "James" and an important person. I might call him "Jimmy", "Jim" or "J", say.*
If I was taking about him to friends, I might naturally call him any of those.
If I was talking about him in a more formal context (eg to his employees or just people who don't know him personally) I'd probably call him "James" or even "Mr LaM".
If I said him "J (that's what I call him) ", the implication would be, imo, that I know he's important but I, LaM, get to call him by a pet name.
You must call him "HRH", "Sir", prince Harry or whatever.
Massively over-thinking, I realise, but I do question my own motives and had been wondering why H-as-I-call-him makes me wince.
*The thought of Mr LaM as an important person is making me smile a bit.
**Obviously, I call him "Lord-and-master lion", as is correct and proper.