Mr Darcy

This has been bugging me for years now. I can't even remember where or when i saw it.

It's a Black and white film in made England. Set in Europe as the end of WW2 is coming. A British platoon is holed up in a house in Germany, down at the end of the street is a german pillbox. The Brits are marking time till the end of the war they are leaving the pill box alone and just counting the days till its all over.

They wake up one morning to realise that one of them is missing. They search the house and eventually realise that in front of the pillbox is a shell crater and their mate is lying in it. They come to the conclusion that he tried to blow up the pillbox in the night and was wounded. The rest of the film is a tense description of them trying to get their mate back. In the end they blow up the pillbox to recover him only to find that he'd found a bottle of booze the night before and got wasted and just wandered out in front of the pillbox to sleeep it off!

any ideas?