Who wrote the poem with the first line (as well as I can remember): 'This is the night mail/train (?) crossing the border, bringing the cheque and the postal order, letters for the rich, letters for the poor...' Any full copies of it online?
A highly influential two-reel documentary made for the GPO Film Unit, building up an exciting pattern of images and sounds as the night mail train steams from London to Scotland. The verse which largely replaces commentary was written by W H Auden. There is an audio copy at http://ds.dial.pipex.com/town/plaza/dg40/griersont rust/nightmail/nightmail.htm