However, Brooke was best known as a book illustrator. WorldCat library records show that he illustrated several works by Mrs. Molesworth in the mid-1890s, perhaps from 1892; one was The Carved Lions (1895) in its first edition. His skillful and witty illustrations in Andrew Lang's Nursery Rhyme Book (1897) established his reputation as a leading children's book illustrator of pen-and-ink line drawings and watercolors. His acclaimed works include Johnny Crow's Garden (1903), "Ring O' Roses", "The Golden Goose Book", Johnny Crow's Party (1907), Johnny Crow's New Garden (1935), "The Nursery Rhyme Book", and "Oranges and Lemons" published by Frederick Warne & Co.
