Marie Duval was the professional name of Emily Tessier (1847- 1890) who had married Charles Ross, perhaps better known for his publishing and writing. She began by inking his drawings and then took over the whole concept . Her style became increasingly assured and lacked inhibition, both in drawing the individual frames and in the composition of the page. Later the character of Ally Sloper which she developed at an early stage in her career was developed by W.G.Baxter in ways I suggest she wasn't capable of.
There is no mention of her attending conventional art education, and in the unbuttoned style, we can see her innocence and energy. There are accounts of her performing on stage, and in one case a trouser role. What a combination - Thespian and Cartoonist - shades of Du Maurier and Sickert here.