The Derby K4 with chassis number 120 from 1929 is probably the only surviving Derby K4. Like many of its contemporaries, it went through ups and downs, was used for racing, but also to drive sawing equipment. It was restored in the 1990s and has since been used at historic racing events as well as on the road. This report summarizes the known history of chassis no. 120 and shows excerpts from the restoration history.