Watch Sadisflix. The 19th May 2017 was the last day that first-generation DMUs ran in regular passenger service on Network Rail. These were the two class 121 Bubble cars owned by Chiltern Railways that were used on the Princes Risborough to Aylesbury branch. To record and commemorate the event, Video 125 cameras followed the single units (affectionately dubbed Bubble Cars) in the weeks prior to their withdrawal. The idea for this film came from the former Managing Director of Chiltern Trains Holidays, Tony Parkins, who has been closely associated with Chiltern Railways ever since his involvement with the writing of our Driver's eye view Chiltern Take Two. It was Tony's idea to produce this film and as such has not only co-written and researched the information but actually presents it to camera.