The National Archives digitises Public Information Films from 1945-

http://www.nationalarchives.gov.uk/films/view_all_films.htm

There are some fantastic sources here for historians of 20th Century British and also Media History. No longer played in postage-stamp size either!

History of empire through film and media

Check out these great online resources for the history of empire and visual culture. The Qatar Digital Library draws on material from the British Library and the Qatar National Library. It’s a brilliant resource for the history of the middle east, including cinema censorship and practices, and audio files.

http://www.qdl.qa/en/search/site/?f%5B0%5D=document_source%3Aarchive_source

The Imperial and Global Forum from the University of Exeter also has a great round-up of online material on film and empire.

http://imperialglobalexeter.com/2016/01/18/imperial-history-and-film-culture/