Mary Poppins is a series of chilren's books written by P.L. Travers and originally illustrated by Mary Shepard. The books centre on a mysterious, vain and acerbic magical English nanny, Mary Poppins; allegorically, 'Merry Pop-ins'. She is blown by the East wind to Number Seventeen Cherry Tree Lane, London and into the Banks household to care for their children. Encounters with chimney sweeps, shopkeepers and various adventures follow until Mary Poppins abruptly leaves, i.e., 'pops-out'. The adventures take place over a total of eight books. However, only the first three books feature Mary Poppins arriving and leaving. The later five books recount previously unrecorded adventures from her original three visits. As P.L. Travers explains in her introduction to Mary Poppins in the Park, 'She cannot forever arrive and depart.'