How did a bag of rubbish help 2nd Lieutenant Peter Douglas escape a German Prisoner of War camp in Poland?

Douglas was one of the many 8th Argylls wounded and captured at St Valery. He was imprisoned in Salzburg but volunteered to move to a new camp in Poland. He escaped, with Polish help, by hiding in the rubbish. He made it to Danzig and stowed aboard a neutral Swedish ship to Stockholm.

Main Image:
2nd Lieutenant Peter Douglas, 8th (The Argyllshire) Battalion pictured in 1940.

What a load of rubbish