Visible crew/equipment: Just before Starbug crashes and Kryten says they will have sandwiches for lunch, a boom mic can briefly be seen above his head. (00:09:45)
Visible crew/equipment: During the scene when Starbug crashes, the camera then does a barrel roll and you can see wooden roof beams of the set and the stage lighting. (00:09:55)
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