Robin is Eva Kane's "son", Evelyn, which can be a man's name as well as a woman's. Mrs Upward had not known who was the mother of her adopted son, but he realised that any scandal would be to his detriment. Mrs McGinty saw the photo of Eva Kane while working at the Upward house and assumed the photo was of Mrs Upward as a young woman. Robin killed her to prevent her from telling anyone who might recognise the photo, and framed Bentley by stealing the £30, correctly assuming Bentley would incriminate himself by panicking. Mrs Upward thought Kane's photograph to be similar to a photo Robin had shown her of his mother, whose back story he made up. She wanted to confront Robin by herself, so she pointed to the wrong photo (that of Lily Gamboll) to put Poirot off the scent.