From 1934 to 1939, he is the editorial and lay-out secretary at a Belgian weekly, L’OPINION PUBLIQUE, and, always writing, publishes several articles and stories in other magazines and papers.
World War II causes an interruption of his career: he is taken prisoner on the Albert Canal.
In 1945 he returns to the popular (but short-lived) dailies as deputy chief editor of L’INFORMATEUR-MIDI, then moves on to the audiovisual world, writing promotional texts for Radio Luxembourg, and working as a scriptwriter and first operator in the cinema studio of Claude Misonne (1947).
From 1949 to 1955 he edits the scripts of more than 500 short cinema advertisements for the Vandam-K.H. agency. One of them even wins the Grand Prix International de la Publicité. It occurs to him that this experience has taught him to think compactly, because the advertisers want maximum results from a minimum of expensive time.
René Follet introduces him to Jean -Michel Charlier in 1951. World’s Press, where Charlier is employed as an all-round writer, has just launched “Les Belles histoires de l’Oncle Paul” in SPIROU. Overworked and dreaming of a career as a pilot at SABENA, Charlier is looking for someone to take this series off his hands.
On 9 August 1951, Joly publishes his first Oncle Paul (Comment naquit la Marseillaise), illustrated by Dino Attanasio. More than 1100 stories will flow from his inexhaustible documentation until the series end in 1976. He also contributes to several dozens of stories of L’Histoire Vivante in the weekly BONNES SOIREES.
In 1955, Joly decides to devote himself exclusively to writing scripts for historical comic strips.
World’s has offered him a contract for the annual delivery of 50 scripts of Oncle Paul and at the same time he writes several major biographies: Stanley (illustrated by Hubinon in SPIROU), Marco Polo (started by Uderzo and finished by Pierre Dupuis in LA LIBRE JUNIOR), Tom et Nelly, enfants du siècle (started by Uderzo in RISQUE-TOUT and continued by Bielsa in SPIROU), Winston Churchill (illustrated by Eddy Paape in SPIROU), Leonardo da Vinci (for Pascal in SPIROU).
He even contributes, briefly and discretely, to the first few issues of PILOTE with Eddy Paape: the historical story “La Merveilleuse histoire de Saint-Nicolas”, as well as several games pages.
In the late 70s he gradually works toward his well-earned retirement, delivering one more Histoire en mille morceaux (in which a complete historical anecdote is compacted in each plate). He dies in Brussels on the 7th of June, 1988.