Witjas worked as a young man as a Diamond cutter in Antwerp. In 1914 he fled Belgium during the first world war to his neutral homeland. Initially he worked as a violinist, but he soon came in contact with the popular comedian Painter. For ten years he made (as ' the genre ' diseur) part of his company.
After the murder of Painter in 1927 took Collin for some years the leadership of the company over. Later he led the ensemble "The Troubadours." He not only sang French chansons, but also Dutch work of Painter,Dirk Witte and Koos Speenhoff. During the Second World War , he was hiding in Wildervank. His mother, Esther Witjas-Kinsbergen, died in the Auschwitz concentration camp.
After he rather suddenly put an end to his stage career was Collin "rediscovered" by Wim Ibo. KRO In 1964 banned the broadcast of his portrayal of Wittes fifty-year-old song "the pears" over the marketentster Jopie, that pears sold to soldiers, but also further so that they could shoot well with them on at the end remained sitting with "the baked pears of the whole battalion". Collin remained up to its eightieth occur.