 Their most famous lineup featured Reinhardt, Grappelli, bassist Louis Vola, and rhythm guitarists Roger Chaput and Joseph Reinhardt (Django's brother) who filled out the ensemble's sound and added occasional percussion.According to Grappelli, the group evolved from a series of backstage jams originated by Django Reinhardt, with Stephane Grappelli, at the Hotel Claridge in Paris, where the two were engaged as members of a band led by bassist Louis Vola.After a series of informal jam sessions at the Hotel Claridge, concert promoters Pierre Nourry and Charles Delaunay (leaders of the "Hot Club de France", a society chaired by Hugues Panassié devoted to the appreciation of jazz) urged the formation of a permanent group.