Christie frequently used quotations from nursery rhymes as titles for her novels and short stories. Sometimes the reference is a clue to the solution but, infuriatingly for those who treat her novels as puzzles to be solved, at least as often it is a red herring.

The most frequently quoted rhyme is “Sing a Song of Sixpence”, whose words give the titles to the Miss Marple novel A Pocketful of Rye (from the Folio Society edition of which, the Andrew Davidson illustration above is taken) and to two short stories Sing a Song of Sixpence and Four and Twenty Blackbirds.

In the novel, Inspector Neele seeks obsessively for the reason why the murder victim should have “a pocketful of rye” in his jacket when he is killed. It would give too much away if I were to disclose the reason here and its connection, if any, with his death.

In the first of the two short stories, there is indeed a sixpence, possibly forged, which has come into the possession of the woman who is murdered. It’s place in the solution suddenly occurs to the investigating lawyer by chance when he sees the name of a restaurant called “Four and Twenty Blackbirds” – the association with the rhyme triggering a line of thought which leads to the unmasking of the culprit.

The second of the short stories turns on the effects of eating blackberry pie, which reveals a surprising sequence of events by which a murder was contrived. Needless to say, Poirot, sees through the concealed plot and springs the surprise conclusion.

Of course, it is Christie’s intention to spring such surprises and it is no surprise, therefore, that she should use this nursery rhyme more than any other as a source for her titles. The rhyme relates the 16th century practice of concealing live birds in a baked pie served up between courses in a banquet. When the pie is cut open, the birds emerge and fly off (or begin to sing, as the rhyme has it), making an entertaining surprise for the guests. Surely this is only appropriate for Christie as the Queen of springing such surprising denouements on her readers.

The nursery rhyme “Three Blind Mice” also appears in three Christie works.  It serves as the title for a short story and a radio play. It is also used as a musical motif in the long-running production of her play The Mousetrap. However, I would argue that since all three are inter-related – the short story is based on the half hour radio play and the long play is an expansion of the ideas first contained in the shorter original, albeit with crucial differences – this constitutes a single actual use with three different takes rather than three separate and unrelated stories.

Other rhymes which have been used by Christie are many and varied in how she has applied them.

“Goosey Goosey Gander” is used in the Tommy and Tuppence adventure N or M?.

“Hickory Dickory Dock” gives its name to a Poirot novel although the link is thin – the name of a road in the book, indeed, the US title of the book is Hickory Dickory Death, which makes the link even more obscure.

“Mary, Mary Quite Contrary” is used in the short story How Does Your Garden Grow?, the rhyme being quoted by Poirot as he explains how he arrived at the solution.

“One, Two Buckle My Shoe” gives its name to the title of a Poirot novel, though again the US title differs. It was first known as The Patriotic Murders and subsequently re-titled An Overdose of Death. Perhaps the rhyme is less well known in the US than the UK, or perhaps the publishers thought the references were too obscure for the American market. However, the chapter titles in this book are derived from the lines of the rhyme, so it does provide valuable signposting to the reader who is alive to the possible connotations of the rhyme, to help solve the mystery.

“There Was A Crooked Man” serves as an inspiration for one of Christie’s favourite of her novels, The Crooked House, for which she allowed the idea a period of several years gestation before she finally wrote it. The rhyme has everything crooked and this is applied to the psychological states of the family members living at the house who have all grown up “twisted and twining” as a result of an unnatural dependence on the family patriarch.

“This Little Piggy” provides plot ideas for the novel Five Little Pigs. The five suspects are each noted by Poirot to have characteristics that might be (loosely) associated with those of the five pigs listed in the nursery rhyme. Again the US publishers eschewed this conceit and retitled the book Murder in Retrospect.

But of course the most famous (infamous?) use of a nursery rhyme by Christie was her riff on “Ten Little Indians” or, in its more politically incorrect original form “Ten Little Niggers”, now more suitably titled And Then There Were None, taking the final line of the rhyme. Here the rhyme serves as a blueprint for the deaths which befall each of the characters in the startling plot. It is a masterly use of this device which both ratchets up the tension and provides the mis-direction to take readers’ eyes off the ball at the crucial moments so that they are shocked by the final revelation of who is behind the deaths. It is little wonder that this book was recently voted her most popular with readers – it has sold more than 100 million copies, making it the seventh ranked in the all time best-sellers by any author and contributing significantly to her position as the best selling author of all time.