These are some i can think of with a British Theme @TheLastColdBeer,
1) Dunkirk
2) The Dam Busters
3) The Eagle Has Landed
4) The Battle of Britain
5) Bridge over the River Kwai
You probably heard or seen some of these, especially like Bridge over the River Kwai which won a few Oscars i think, Dunkirk is often shown over here, shows the disaster at Dunkirk and the heroism of ordinary people who went in their fishing Boats to try and rescue the British and French troops from a massacre, great movie, you can watch the movie Dunkirk or i posted a TV version we done for the UK a few years ago which was very good and probably goes into it more then the movie does, think the TV version was done by the BBC if you want to search for it, both worth watching, The Battle of Britain is quite a famous movie too with some unbelievable flying scenes and of course it features the greatest airplane ever built, the Spitfire.
http://www.youtube.com/watch?feature=player_detailpage&v=8u0Vsyt2PaM
http://www.youtube.com/watch?feature=player_detailpage&v=KZ-2X609LRE
http://www.youtube.com/watch?feature=player_detailpage&v=sXs0-cFMERo