another British war movie title request

[prc1966]

Back in my high school days, in the early 1980's, I recall once watching a British war movie on A&E one Saturday evening. It was in color, and I think it was from the early to mid 70's. The only thing I recall is that it was about some British military personnel trapped nehind the lines in Holland or Belgium, or maybe France. I think they were pilots, but perhaps they were army soldiers trapped behind the lines. The only scene that sticks in my mind is one scene in which the two men are hiding in a wooded area, and passing the time by repeating slightly off-color limericks to one another.

 

Anyone recognize the film?

[ChiO]

But for "color" and "mid 70's", it was sounding like *One of Our Aircraft Is Missing* (Powell & Pressburger, 1941).