Mary Poppins is the lead character in a series of eight children's books written by P. L. Travers. Throughout the Mary Poppins series, which was published over the period 1934 to 1988, Mary Shepard was the illustrator. The books centre on a magical English nanny, Mary Poppins. She is blown by the East wind to Number 17 Cherry Tree Lane, London, and into the Banks's household to care for their children. Encounters with chimney sweeps, shopkeepers and various adventures follow until Mary Poppins abruptly leaves, i.e., "pops-out". Only the first three of the eight 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."