Mrs. Banks did not notice what was happening behind her, but Jane and Michael, watching from the top landing, had an excellent view of the extraordinary thing the visitor now did.
Certainly she followed Mrs. Banks upstairs, but not in the usual way. With her large bag in her hands she slid gracefully up the banisters, and arrived at the landing at the same time as Mrs. Banks. Such a thing, Jane and Michael knew, had never been done before. Down, of course, for they had often done it themselves. But up — never! They gazed curiously at the strange new visitor.

Ch. 1 "East-Wind" - Mary Poppins (1934)