In pre-Electric London, frequent catastrophically destructive theatre fires can be speculated to have accelerated the pace at which the architectural typology of the theatre evolved, with fires creating opportunities to rebuild in new forms, and driving architectural change through the quest for more effective fire-prevention. Employing Lamarckian evolution as the framework for architectural typological study, a genealogy of London’s historic theatres can be constructed, where fire is the means of procreation. Within this genealogy lies the potential for tailored flexibilities within new theatre architecture, arising through the continuous evolution of morphology over generations, as well as latent architectural form born out of the physical and regulatory constraints of auditoria.