"On with the Motley" was an operatic aria which the Sixth Doctor sang. Mel cited his rendition of the song as evidence of his musical inability. Upon departing the Hyperion III, she told Commoodore Travers that he should "count his blessings" that he had never heard the Doctor sing the piece. (TV: Terror of the Vervoids)
Behind the scenes Edit
The Doctor was heard to sing the song for about two seconds at the end of the penultimate scene of Vervoids. The tiny snippet helped Big Finish later plausibly assert that the Sixth Doctor might very well be a "singing Doctor" and therefore capable of the musical that was Doctor Who and the Pirates.