The range of Grahame's books is extraordinary. FArTHER is supremely sensitive, Wisp is very evocative, and The Rhythm of The Rain is both informative and yet has a charming narrative. (And there will be more books to follow it up soon.)
On the other hand, the detail and the many different styles he's used in Life, The First Four Billion Years demonstrates his lifelong passion for the history of the Earth and its inhabitants. The Wind in The Willows gave him the chance to indulge in his own interpretation of a story we all know so well.