In 1953, the BBC filmed a non-stop train journey from London to Brighton. Thirty years later, in 1983, they did it again. And this year, they've filmed it for the third time, and spliced all three recordings together.
The result is this hypnotic rail travel video.
Southern Railway had to lay on a special train early on a Sunday morning for this video, as there are now no non-stop train services between London and Brighton, explains BBC South's transport correspondent Paul Clifton, who took the journey this year.
"The film is a fascinating social barometer, as well as a record of how the railway itself has changed," he says.
To the casual observer, the journeys look remarkably similar when placed side by side. But look closely and you'll see some marked changes.
Dress code has changed dramatically, as have the sheer volume of passengers.
And by 1983 and 2013, you can see far more trackside vegetation. In the steam era, trees were cut back to reduce the risk of fires from hot ash.
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