It’s not Citroen, but it is a rather historic film:  A Jaguar “factory tour” dating from the early 1960’s.  (Notice the E-Type in the background).  Quite the era!  We wonder if Citroën UK’s Slough factory would have looked somewhat the same?   The Citroën factory, in the Slough Trading Estate was opened on Feb. 18, 1926 and cars were built there until 1965.

https://www.youtube.com/watch?v=lKJPFRNO344