Artist and illustrator John Worsley, who made the model of "Albert" for the film, had performed the same task in the the real P.O.W. camp, where he had been assisted by the film's technical adviser Senior Commissioned Gunner (TAS) Lieut. J.W. Goble.
The character played by Anthony Steel is based on John Worsley, who created "Albert" in the real-life story and then for the film.
A fake POW camp was built on Headley Heath for this production.
As the opening credits state: "The events concerning Albert are based on fact, and took place in the prison camp, Marlag "O", for Naval Officers in North West Germany, during the spring of 1944."
After the German guard orders Texas to take off his chronometer watch and Texas flatly refuses, the guard walks off, defeated, towards the camp brass band which is playing the William Tell overture. Suddenly the three trombonists stand up and blare out the first line of Colonel Bogey (to which the words "Hitler has only got one ball" were commonly sung during the war) as a taunt to the guard.