Visible crew/equipment: When Ace Rimmer is talking to Mellie, a boom mic can be seen at the top of the screen. (00:04:05)
Visible crew/equipment: When Rimmer is speaking to Lister about how Ace Rimmer got all the breaks in his life, a boom mic can be seen in the top left of the screen. (00:24:15)
Answer: The cello is a large four-stringed instrument, which, when it is played, stands vertically on the floor between the player's legs (assuming they are seated). If it is to grow as large as the other instuments mentioned will, it would require a rather unseemly lack of femininity to be able to encompass it with the legs.
Rooster of Doom