There are many artists from the 1930s that we simply know little about
One such is G S (Stan) Brien
Brian produced 6 posters for Shell including the Chamois Quick Starting Pair, Summer Shell with the swallows, Cheetahs Quick Starting Pair, Hares Quick Starting Pair and a second Summer Shell poster.
He also did book illustration in the early 1930s and remained active until 1935
From LT website
G Stanislaus Brien, born in Poland. Designed posters for London Transport 1935 Biography: G Stanislaus Brien was a lino-cut artist. He exhibited at the Redfern Gallery in London between 1930 and 1931. As well as the Underground, he designed posters for the London & North Eastern Railway and Shell.
The quality of his work is undeniable