Sing a Song of Sixpence

Previously published in the print anthology The Witness for the Prosecution and Other Stories.
Retired Scotland Yard detective Sir Edward Palliser is called upon by Magdalen Vaughan to help solve the murder of her wealthy, eccentric aunt, Miss Lily Crabtree. The authorities believe only members of the household could have committed the crime, and this suspicion is tearing the family apart. Who really killed Lily's aunt?