Reginald L. Knowles (1879 – 1951) was a book designer and illustrator who worked with his brother, Horace Knowles, on a number of exquisite illustrated books in the first two decades of the twentieth century, including Legends from Fairyland (1907), Norse Fairy Tales (1910) and Old World Love-Stories (1913).
While both brothers usually share equal credit, it is understood that most of the colour illustrations and detailed monotone images were prepared by Reginald Knowles who signed "RLK" (ie : Everyman's Library).
The work of the Knowles' brothers drew influences from Art Nouveau, Victorian Fantasy and Gothic Revival imagery.
A decade after their earliest work, Horace Knowles produced a stunning and comprehensive suite of colour and monotone illustrations for Peeps into Fairyland (1924).
In later life he illustrated the angling books of Wilfred Gavin Brown: "My River and Some Other Waters" (1947); Angler's Almanac: Some Leaves On A River (1949).
Source: Wikipedia, "Reginald Knowles", available under the CC-BY-SA License.