Board Thread:The Panopticon/@comment-4028641-20151101035254/@comment-24894325-20161126193916

Yes, you are right. It's been months, so the questions and arguments need to be repeated in full. I propose to decide question 1. first and separately from the other three. The facts are as follows: The last item has appeared only about a week ago and, to my mind, resolves the situation. Here is why.
 * Petronella being her first name was stated in-universe by Osgood.
 * The name Petronella was used by the Doctor in-universe (essentially) in the same conversation.
 * Ingrid Oliver is credited as Petronella Osgood (for the first time) in the latest audio box set.

While "Petronella" originated in-universe, it only had one subjective source: the Doctor learned about the name from the same source, i.e., from Osgood. Thus, we considered two possibilities: (A) that Petronella is her first name or (B) that she lied/joiked for one reason or another about her first name.

Although cast lists on Big Finish website are not in-universe per se, I believe cast lists have more weight than any other out-of-universe source (script, etc.). Partly, this is because TV stories (and at least one audio story) feature cast within the story. Cast is an inalienable part of a TV story. For instance, the spelling in the cast is normally preferred to, Radio Times listings, promotional materials or closed captions. It is true that cast has sometimes been used for misdirection. But in all cases I can remember, it was by stating character's name that was at least partially correct within the context of the story and never by stating a character's name that is just false (the name of the actor, on the other hand, may be wrong). For instance, the character of Lucie Miller is credited as "Brother Lucianus" in The Book of Kells, but she is called by that name in the story. And this is why it is important that Osgood is never called by the first name (Petronella or otherwise) in the UNIT: Silenced box set. Hence, Petronella cannot be a partially correct but misleading name. The only option remaining is that it is her first name.

To summarise, the only thing that could overwrite a name stated in the cast is an in-universe information expressly contradicting this name. In the absence of such contradicting information, I believe we should rule out option (B) and accept Petronella as the first name (at least until a contradicting information occurs).