Hi, this is my first posting here and I would really appreciate your help!

I saw this film on tv as a kid in the late 70's and it made a lasting impression. It was in B&W (but that could have to do with the tv-set).It happens during WWII and England is under attack. The story follows a little boy and a old man(grandfather?). During the night, fallen english soldier's from previous war's rise to help saving England. I guess a little magic is involved but my memory is a little unclear about this. You never see the soldiers, only the uniforms, helmets, weapons etc.
Anyone know the title? And if it's avaible on DVD?