Does he? “Here’s a phrase I use, and what it means” seems fine to me. There might be a bit of personal history why he chose a plumber, but I’m guessing he doesn’t remember.
> Simon Orrell: My first exposure to “The Plumber Problem” was sitting in a theatre with my dad in 1973 watching “Emperor of the North” and my dad leans over to whisper, “They didn’t make culvert pipe like that back in the ’30s. It was plate, not corrugated.”