Davis first found wide acclaim when he stood in for an ill Otto Klemperer in a performance of "Don Giovanni", at the Royal Festival Hall in 1959. A year later, Beecham invited him to collaborate with him in preparing "The Magic Flute" at Glyndebourne. Beecham was taken ill, and Davis conducted the opera. After the "Don Giovanni", "The Times" wrote, "A superb conductor of Mozart declared himself last night at the Festival Hall…. Mr Davis emerged as a conductor ripe for greatness." Neville Cardus in "The Guardian" was less enthusiastic but nevertheless considered that he "had his triumphs" in the performance. After "The Magic Flute", "The Times" called Davis "master of Mozart's idiom, style and significance", although Heyworth in "The Observer" was disappointed by his tempi, judging them to be too slow.