Poirot's secretary, Miss Felicity Lemon, has few human weaknesses. The only mistakes she makes within the series are a typing error during the events of Hickory Dickory Dock and the mis-mailing of an electricity bill, although she was worried about strange events surrounding her sister at the time. Poirot described her as being "'Unbelievably ugly and incredibly efficient. Anything that she mentioned as worth consideration usually was worth consideration'." She is an expert on nearly everything and plans to create the perfect filing system. She also worked for the government agent-turned-philanthropist, Parker Pyne. Whether this was during one of Poirot’s numerous retirements or before she entered his employment is unknown.
Miss Lemon has a sister, Mrs Hubbard, who is a warden at a student hostel on Hickory Road.
In The Agatha Christie Hour, she was portrayed by British actress Angela Easterling, while in Agatha Christie's Poirot, she was portrayed by Pauline Moran. A marked difference from the text exists in Moran's portrayal, where she is shown to be an attractive, fashionable and emotional woman showing an occasional soft corner for Poirot. In Agatha Christie's Poirot, Miss Lemon was also shown several times intend to dabble in the occult arts such as divination with the I Ching, read tarot cards, practice hypnotism and use a planchette to communicate with the spirit world.