Alethea Garstin (1894–1978) was a Cornish artist and illustrator; she was the daughter and pupil of painter Norman Garstin.
Biography on Wikipedia: https://en.wikipedia.org/wiki/Alethea_Garstin
The Reverend Charles Francis Benthall on Holiday in Morocco by Alethea Garstin
c.1925 / Oil on canvas / 39″x31-1/10″ / Benthall Hall, Shropshire, UK
Alethea Garstin on Artnet: http://www.artnet.com/artists/alethea-garstin/