Ive just found this:
KIRTLEY JOHNSON CO
Its a film made in 1962 by the BBC in their series "Railway Roundabout"
It is also available as part of a DVD published by
www.dukevideo.com
It was my local line. I can just remember an LMS passenger train (probably a "push pull") waiting on the branch platform at Duffield.
Later it was used for testing the early prototypes for the Derby Lightweight DMUs (so "Iris" is back home after sterling post-retirement for the Research Department.)
In addition the film starts with the south end of Derby station and works the way it used to be so it's all pretty nostalgic.