Firman’s first job, at the age of thirteen, was at the Playhouse Theatre, London, where he was part of a quintet playing entr'acte music.
After only three months in this job he secured the part of Sascha, a gypsy violinist in the musical Sally at the Winter Garden Theatre, Drury Lane.
During this run, at the suggestion of the producer, George Grossmith Jr., Feuerman changed his name to Bert Firman, apparently so as to make it easier to bill in lights outside the theatre.
The group included such prominent musicians as Sylvester Ahola, Chelsea Quealey, Frank Guarente, Arthur Lally, Danny Polo, Max Goldberg and Jack Jackson.
The band included Sam Costa, a young pianist who would later become a singer and actor, as well as Freddy Gardner, a talented British saxophonist.
At the outbreak of war Firman moved to the Cafe de Paris with a band that included Ivor Mairants and George Melachrino.