Alongside Werner and Charlie Brooke, the Stockrise brothers also appear in both volumes of The Adventures of Jo, Zette and Jocko: Mr Pump’s Legacy and Destination New York.

He was fascinated by new techniques in the medium – such as the systematic use of speech bubbles – found in such American comics as George McManus' Bringing up Father, George Herriman's Krazy Kat and Rudolph Dirks's Katzenjammer Kids, copies of which had been sent to him from Mexico by the paper's reporter Léon Degrelle, stationed there to report on the Cristero War.

Courtois was often unhappy with elements of Hergé's work, and had recently complained about a scene in his latest story, The Broken Ear, in which the two antagonists drown and are dragged to Hell by demons.

Whereas Tintin had no parents and did not go to school, they wanted a series in which the protagonists had a family and acted more "normal"; they also requested that these characters have their adventures in France.

"[6] Taking on Jo, Zette, & Jocko alongside The Adventures of Tintin and Quick & Flupke, Hergé soon found himself overworked, and put the latter series on the back burner.

[6] For New Year 1938, Hergé designed a special cover for Le Petit Vingtième in which the characters of Jo, Zette and Jocko were featured alongside those from The Adventures of Tintin and Quick & Flupke.

[7] Hergé was unhappy with the series, commenting that its characters "bored me terribly, these parents who wept all the time as they searched for their children who had gone off in all directions.

Hergé had asked the French comic book creator Greg (Michel Regnier) to provide a scenario for a new Tintin story.

Sometime after this, Hergé sought to resurrect Le Thermozéro as a Jo, Zette and Jocko adventure and instructed his long-time collaborator Bob de Moor to work on an outline.

[11] Commenting on The Secret Ray, Hergé biographer Benoît Peeters noted that it "used rather conventional elements to vivid effect", using many clichés from popular novels such as a robot, a mad scientist, and gullible cannibals.

"[6] When discussing its sequel, The Stratoship H-22, he thought that it had been "conceived in almost a single burst" from a "general framework", in this way operating in a more linear fashion than he did with his Adventures of Tintin.