At school 50+ years ago the school Railway Society (an amalgamation of the Locomotive Society and the Model Railway Club) used to meet Friday lunchtimes and several times a year we used to show British Transport Films – free to the school except for the return postage. All are now availble on dvd and many on Youtube or BFI as well.
We used to charge a nominal fee as far as I can remember, but as projectionist (they were all on 16mm) I got in free.
Favourites included 'Elizabethan Express', 'Giants of Steam', 'Snowdrift at Bleath Gill' and 'Lets go to Birmingham' and of course 'Night Mail' if the Benjamin Britten score is not too modern for you.
'A Letter for Wales' is only available on dvd but has some good shots of steam locos and a Hunslet quarry tank at work in its original setting.
An amazing film showing exactly what NOT to do to stay safe near the railway is 'The Finishing Line' Full version is 20min with lots of fake blood and gore!'
Nick