What is the title of this winter book?

Question

It was about 2 children, sister and brother, (I think the girl was called Dorothea) and they moved to a new place, and met a new group of kids who taught them how to do all types of codes, like Morse Code, Semaphore etc. I think the boy fell out of a tree as well. It was something like 'Winter's Tale', i think, have searched on google, just cannot find it. Would love to read it again!

Answer 1

"Winter Holiday" is the fourth novel of Arthur Ransome's Swallows and Amazons series of children's books. It was published in 1933. In this story, the third set of major characters in the series, the D's — Dick and Dorothea Callum—are introduced