Elinor M. Brent-Dyer's Chalet School series is one of the most impressively-long series of children's books of all time (Nancy Drew and the Babysitters' Club may beat it, but I believe both of these had the help of ghost writer.) I can't think of a longer-running school story series, spanning 58 books (or 62 if you count those that here split into two for their paperback release.) Beginning in the mid-1920s and ending around the '60s, the books follow the fortunes of a family-run school from its humble beginnings with a handful of pupils in an Austrian chalet, through the Anschluss and World War 2 when they had to flee first to Guernsey, then to the Welsh/English Border, until the school grows so big that it has hundreds of pupils and multiple sites in Britain, Switzerland and a finishing branch.
Of course, through such a long-lived series, the tone and quality is variable, and I like best the early books, when the school is still small and family-like, when you get to know all the pupils, staff and their families, and all their foibles. The second book in the series: Jo of the Chalet School is full of such cosy, informal scenes, and best of all are the Christmas chapters, when headmistress Madge Bettany, her younger sister Jo and a couple of honorary members of the family, spend their first Christmas in Austria, visiting the family of two of the pupils who live in Innsbruck. After a term of Jo and Madge being student and teacher, they get to spend Christmas as sisters once more, in some heartwarming, cosy scenes.
Even now German and Austrian Christmas markets are a thing of wonder, replicated in city centres up and down the UK, but even more wonderful, surely, would be the real thing. My Christmases were illuminated with European folk tales alongside the British and American traditions, and in Jo of the Chalet School, Joey and Madge get to experience for themselves of the magical, Christmas-card beauty of an old-fashioned Austrian festival season. Though the girls find some of the ways of their Austrian friends a little old-fashioned, the welcome is warm and genuine, and they spend their first Christmas abroad with tobogganing, skiing and Midnight Mass, their hosts dressed in traditional costume so that, as Jo says, "It's like Hans Anderson, or Snow White and Rose Red come to life!"