For the last 30 years I've been trying to remember a particularly enjoyed air war movie. I'm fairly certain it was British-made, shot in B/W, made during the war.

It concerns a flight of damaged bombers, possibly B25s, left behind to fend for themselves so as not to slow the undamaged craft on their return flight across France towards the English Channel. A lone Spitfire (or Hurricane?) comes upon them, indicates that he's run out of ammunition and will accompany them. Naturally a squadron of enemy fighters appear and the lone RAF chap proceeds to lead them past the damaged bombers who still have ammunition in their guns. This works for a while, by which time the channel has been reached, but our hero is shot down within sight of the White Cliffs of Dover while the dmamged aircraft fly on to safety. End.

Any help in IDing this movie would be appreciated. The best movie minds in Australia have tried, and failed.