Grace Ritchie is a non-canonical character created for the 2013 ITV adaptation of Greenshaw's Folly. She is a friend of Miss Marple and a fellow member of the knitting circle of St Faith's Orphanage. Grace Ritchie is portrayed by Joanna David.
Just around the time that it was believed Miss Greenshaw was believed to have been shot by an arrow, Grace picked up the phone at the orphanage and heard a faint voice. The speaker claimed to be Miss Greenshaw, muttered a few words and then the line went dead. According to Grace, Miss Greenshaw asked for fish. Grace thought she heard her asking for "a mound of cod", "a pile of carp" or "a heap of haddock" or words to this effect. Understanding what exactly the words were eventually proved critical for Miss Marple in solving how the murder of Miss Greenshaw had been committed. This plot element was not in the original short story but was borrowed from the short story The Thumb Mark of St. Peter.