Although Mackenzie composed a large number of works, which met with great public success, he found, as had Arthur Sullivan earlier and as did Parry contemporaneously, that running a large musical conservatoire left less time for composition. Both at the Academy and elsewhere, he was a popular lecturer. Among his topics were Verdi's opera "Falstaff", the text of his lecture on which was later published in translation in Italy. Outliving his contemporaries Sullivan and Parry, he gave memorial lectures on their lives and works. At a time when Sullivan's reputation in academic musical circles was not high, Mackenzie's tribute was generous and enthusiastic.