Sole British contribution to international peer-reviewed volume originating from the interdisciplinary seminar 'Opera in Context', University of Iowa (2001). The collection is described as 'fresh, intriguing and insightful' (Classical Music, 26 November 2006) and was shortlisted for the 2007 AMS Ruth A Solie Award. (i) Originality: scholars of Italian opera find evidence of an emerging Werktreue aesthetic in Continental opera houses after 1830; but this article argues that a ‘work-concept’ began to regulate performances in London considerably earlier, in the 1810s–20s, and particularly in productions of Mozart. The inter-relationship of London’s operatic and concert spheres, and close links between literary romanticism and opera criticism, are among the factors discussed in accounting for this phenomenon. The article also addresses a significant gap in scholarship on London's Italian Opera, for which the period 1795–1830 has remained largely unstudied. (ii) Significance: the article has significance for the study of emerging canons in Western art music, particularly since it looks beyond autonomous instrumental music (where much of the theoretical work has been done). It models a ‘thick’ holistic approach to the study of opera production in history, informed by institutional archives, legal records, newspaper and periodical criticism, and close comparison of surviving printed and manuscript libretti held in the UK and US (relevant musical sources having mostly perished). Of direct relevance to specialists in reception studies and performance practice is the historicisation of changing attitudes towards the fluidity of the musical work. (iii) Rigour: this is apparent in the exhaustive collation, study, critique, and corroboration of surviving sources which inform the discussion throughout. Line-by-line comparison of different versions of the same libretto is just one example of the rigour demonstrated. This essay works towards a monograph investigating the English reception of Mozart's operas (2012).