I may have found an in-joke...

[Eric Oppen]

No: HPFGUIDX 55737

Having recently re-read George Orwell's essay on "Boys' Weeklies" in a
collection of his essays, I did a web search for "Billy Bunter" and found a
website about the whole "Billy Bunter" series.

Billy Bunter, the "Fat Owl of the Remove," and the hero of the stories, is
in a group called the "Lower Fourth Form," whatever that may mean---in the
stories, he's about fifteen.  One of his form-mates, though, is a George
_Bulstrode._  I wonder if that might have somehow stuck in Our Author's mind
when she was creating the stories?   Being a Yank, I'm not nearly as
familiar with these stories as I would probably be were I British---I've
seen passing references to "Billy Bunter" both in British-written fan
fiction and the "Judge Dredd" comics.

We know that Our Author is busily re-inventing the British "school
story"---could it be that she gave Millicent her last name as a sly tip of
the topper to these famous old tales?