Absinthe?
When Mrs. Bullock was visited in her room by Godfrey (the morning that he started work as the butler), she was in bed recovering from what appeared to be excessive drinking the night before. She made several references to "pixies," and I was wondering if this could have been a not-so-subtle allusion to absinthe, namely, the effect that absinthe is supposed to have on one's overuse of the stuff: it can supposedly invoke hallucinations, which were commonly known as "seeing the green fairy."
So is it possible that Mrs. Bullock was drinking absinthe the night before?