Lucy Elizabeth Kemp-Welch (June 20, 1869-November 27, 1958) was a British painter and teacher who specialized in painting working horses.
Biography on Wikipedia: https://en.wikipedia.org/wiki/Lucy_Kemp-Welch

Forward! Forward to Victory: Enlist Now by Lucy Kemp-Welch
1915 / Artwork for UK WWI recruiting poster, found in various collections
Original painting in Bushey Museum and Art Gallery, Hertfordshire, UK / no details available

Lucy Kemp-Welch on Artnet: http://www.artnet.com/artists/lucy-elizabeth-kemp-welch/

Further reading:
https://www.aigantighe.co.nz/Collection/blog/lucy-kemp-welch
https://homefrontheroines.org.uk/lucy-kemp-welch/
https://www.joyvspicer.com/joy-blog/2016/03/the-sunday-section-art-lucy-elizabethhtml