Has a non-Dickensian character sneaked into Dickensian? Our guest reviewer John Kyriacou and commenter Lesley Cookman have both written about the character of Fanny Biggetywitch (played by Ellie Haddington) and how they've been unable to place her. I consulted Paul Davis's Charles Dickens A to Z, an excellent guide to the various people, places, and things found in Dickens's works, but found no mention of her.
BBC One's character profile for Fanny is here, but gives no clue as to her identity. There are several possible explanations: She could be using an alias, with her real name to be revealed at a later date; "Biggetywitch" could turn out to be the married name of a Dickens character called Fanny whom we've only met under her maiden name; she could be the descendant or the ancestor of someone from Dickens's work; or she could simply have been made up.
Because I haven't yet seen the show, and know nothing about the character beyond what's on that page, I don't know which of these scenarios is likeliest to be true. Your thoughts and theories are welcome in the comment section!