Task: Question Answering
Input (English): Passage: With the piece set to open on 26 December, Gilbert first read the libretto to the cast on 14 December, but Toole, who was playing the central role of Thespis, did not return from a tour of the British provinces until 18 December. He then appeared in nine performances at the Gaiety in the six days immediately after his return, and other actors had similar commitments. In addition, Hollingshead had committed the company to perform a pantomime at The Crystal Palace on 21 December, which included many of the performers who would be in Thespis. Lastly, Thespis was to play as the afterpiece to an H. J. Byron comedy, Dearer than Life, which shared many of its actors, including Toole and Fred Sullivan, and had to be rehearsed at the same time.Despite the short time available for rehearsals, Sullivan recalled that Gilbert insisted that the chorus play a major role, as it would do in their later Savoy operas:
Until Gilbert took the matter in hand choruses were dummy concerns, and were practically nothing more than a part of the stage setting. It was in 'Thespis' that Gilbert began to carry out his expressed determination to get the chorus to play its proper part in the performance. At this moment it seems difficult to realise that the idea of the chorus being anything more than a sort of stage audience was, at that time, a tremendous novelty. In consequence of this innovation, some of the incidents at the rehearsal of 'Thespis' were rather amusing. I remember that, on one occasion, one of the principals became quite indignant and said, 'Really, Mr. Gilbert, why should I stand here? I am not a chorus-girl!' to which Gilbert replied curtly, 'No, madam, your voice is not strong enough, or no doubt you would be.'. 
Question: What is the last name of the person who had an expressed determination to get the chorus to play its proper part in the performance?
Output (English): Gilbert.