A direct predecessor of “Le Masque”‘s and “Giallo” Mondadori’s distinctive yellow covers, Hodder & Stoughton’s “Yellow jackets” series published crime fiction, from 1926 and throughout the 1930’s. Crime thrillers by popular authors such as Edgar Wallace and John Buchan were published there . So were, from 1928, those by Leslie Charteris: this is where all fifty novels in “The Saint” series were published.
Making the link between the original 19th Century railway Library “Yellowbacks” and the fad for giallo (yellow becoming -before noir, the colour of crime fiction) all over Europe, this series of bestsellers anticipate crime fiction paperbacks. While this particular series found an end in the late 1930.s, a new yellow Series was launched in 1949 with the same publisher.
Amongst the successful books published there were the Bull-Dog Drummond right-wing thrillers (in this case this is more of an understatement than a pleonasm) by Sapper (Cyril McNeile, 1888 – 1937)
Authors such as Wallace, Freeman, Oppenheim,and Mason would form part of a canon of books to be published under yellow covers across Europe in the following decade.
I thought the Italian giallos were the first, but it turns out they were the last to jump on the bandwagon. Still, all appeared in the 1920s and I think Italian crime fiction is still called giallos although the covers have changed now.