Joyce Mercer (1896-1965) might be my new favourite illustrator at the moment. Here are her drawings for H. G. Wells's The Magic Shop in this 1930 edition of The Children's Play-Hour Book. Mercer studied at the Sheffield School of Art and at Chelsea School of Art and worked on books, postcards and as a cartoonist for a number of magazines. She trained herself to use both hands so that she could draw simultaneously with both and create symmetrical designs. She suffered some form of 'break' as a result of her experiences in WW1 with the WRVS in the East End of London and spent the rest of her life leading a solitary existence in Penrith in the Lake District.
It's possible to say all kinds of things about her style, which was very distinctive whilst also being utterly 'of the period', however, the two words which come most readily to my mind are 'Joy' and, in no way disparagingly, 'Camp'. There is much more of her work in this children's book alone and so this may not be the last you see of her as a regular reader of Front Free Endpaper. In the meantime her illustrations for Hans Andersen's Tales can be seen here in The Garden of Unearthly Delights.