Decca Navigator System, a flight to Frankfurt in a Vickers Viscount C1960, F190 

A film by Decca, to explain/promote the Decca Navigation System, and its application in aircraft. Examples of its uses show Vickers Viscounts, and the Silver City service. I am guessing this dates to the late 1950s, or possibly the early 1960s.
Lots of interesting information about how Decca navigation systems worked in aircraft back in the day. The system, which had helped with the D-day operation, was made obsolete in 2000.