No, it's not a movie about a logging railroad in N scale, but about the struggles of a young couple to make a go of a decrepit movie theater in the fictional town of Sloughborough, England.

In addition to its small size, antiquated architecture and equipment, and equally antiquated employees (among them an alcoholic projectionist played by Peter Sellers), the theater is located between two elevated railroad lines, and trains on them shake the building in a most wonderful, amazing, and amusing manner. The best example is at 45:00 in the film:

http://www.youtube.com/watch?v=a1gFfQDt0zQ

The movie is newer than I thought to look at it, dating to only 1957.

http://en.wikipedia.org/wiki/The_Smallest_Show_on_Earth

The theater itself was a movie set or prop, built between two bridges on Christchurch Avenue, London NW6, next to Kilburn Tube Station. A replica in the studio was used for close-up shots for things like letters falling from the facade.

Also of interest is the Western movie showing during this sequence. The "star" of our interest is Sierra 18, a 2-8-0, but I'm curious as to which movie this footage was from. It doesn't really matter much, considering how many movies were made on the Sierra over the years, but it would be interesting to know if anybody can identify the flick.

Yes, off-topic, but I found the whole thing fun, and hope you do, too.