"The story behind this lost demo is that May brought the completed Dancer into the studio, where the band (particularly Taylor) was unsatisfied with the lyrics. Taylor had suggested using his own lyrics, and the demo was made. While in the midst of recording the vocals, Taylor decided it would be best to just use the original lyrics, as he felt his voice
didn't fit the song. Taylor did, however, decide to use the drum track from the demo for the final song. Deacon's bass was replaced by May using an Oberheim OB-Xa synthesizer, and the recorded guitar part was cut."
UPDATE: RadioGaga1982 "Of course it's Queen! Taylor plays the first solo, and May switches on the kickass for the second. And? that HAS to be Deacon on bass, it's dead on! Long live the Queen!!!!!!!"