Colditz may have been a notorious Nazi prisoner of war camp, but a newly-unearthed film shows its inmates and guards still found time to fool around.

The extraordinary footage – the only known film of prisoners and guards inside the camp – was found 70 years after it was shot. It will be screened for the first time on Channel 4 tonight.

The clips show inhabitants of the camp in a more relaxed light, joking around and smiling for the camera.

The grainy colour film also shows prisoners gathered for a roll call in the isolated Renaissance castle, which formed the most secure prison camp in the Third Reich.