A couple of things I didn't know about Ibbotson which I found out in the obit. She was born in 1925, which made her 85 when she died. (I never picture my favorite writers as old, somehow.) She published her first children's book at 50. (All right!) She was born in Vienna into a Jewish family which fled to England in 1933. She got a degree in physiology and studied at Cambridge. She married an entomologist. (I seem to recall butterflies playing a role in Journey to the River Sea, which is about the Amazon.)
I'm sorry we'll never see any future books from Ibbotson (unless she left some in manuscript.) And if you haven't read her, you have a delight in front of you.