How Sullivan came to collaborate with Stephenson is uncertain. Just ten weeks before "The Zoo" opened, "Trial by Jury" premiered at the Royalty Theatre, with a libretto by Sullivan's more famous collaborator, W. S. Gilbert. But in 1875, Gilbert and Sullivan were not yet a permanent team. Sullivan had already written two operas with F. C. Burnand, and in late 1874 he had travelled to Paris to see one of Offenbach's librettists, Albert Millaud, although it is not known if anything came of that meeting.