Old movie : wwii escape camp

I want to find a movie.
The old black and white film of an English scientist who did not want to cut his beard landed with a parachute instead of the air force in the uniform of the navy. World War II. The Germans captured him in a camp, but he escaped.
They made funny suggestions for his escape. Like making balloons with chocolate paper.

very important person

⚘👍 Thanks… beautiful memories of the movie I watched when I was a child.