White Midget was going to be the second type of shuttle held aboard Red Dwarf in addition to Blue Midget - the introduction of the character Kryten necessitated the introduction of a larger shuttle. White Midget went through at least one redesign in the concept stage, which changed it to the shape of three spheres like the segments of a bug. It was later renamed Green Midget and later still Starbug.
In the Series VII episode "Ouroboros", a craft called White Midget finally appeared, albeit briefly and only from the stern. It is seen approaching Red Dwarf in a flashback and appears to be a transport/passenger/personnel specialised vehicle as it delivers Dave Lister back to Red Dwarf from his shore leave on Mimas before the accident that wiped out the crew of Red Dwarf.
However, it did not look anything like Starbug or the original design concept. The White Midget model used for "Ouroboros" was actually a converted Blue Midget model, last used in Series III. Mike Tucker and freelancer Alan Brennan refurbished the original model, adding a nose-cone, wings and back engines and repainted it. [1] Because the flashback is of an alternate reality (Kris Kochanski's dimension) and because White Midget has never been seen before or since on the show (including the evacuation of every shuttle in the final episode), it has been theorised that White Midget as seen in Series VII was merely that dimension's equivalent of Blue Midget.