Simon Kellam was a son of Laurence II and Catherine du Sauchoy. He married Catherine Louyse Berthe on 13 June 1652. The couple had at least two children: Thomas (b. 05/11/1657, who would enter the convent of the English Franciscans at Douai) and Simon (still underage in 1674). In 1663 he and his wife entered into a lease with Marie Vanderpiet, widow of the late printer Marc Wyon, for a house in front of the headquarters of the University (the "écoles publiques" in the rue des Écoles). Simon's father Laurence II transferred half of the family's printing office to him in 1655 (Douai, Archives communales, FF 944, 07/01/1655) on the occasion of his marriage. Together with his broter Thomas (II) he applied to the Conseil privé be admitted as a printer in January 1663, some months after the death of his father (Brussels, State Archives, Conseil privé, 1279/23). In 1664 Simon printed two books by the Oratorian father Jean Hanart. In the course of 1664/5 he was paid 4 florins by the town magistrate for having printed an edict (Douai, Archives communales, CC 1031, fol. 15r).