They made a movie about this, a few years back.
They documented the officer’s escape with a few liberties.
Airmen were allowed to visit the local town if they signed out of the “prison”. By word of honor (and treaty?) the agreed to return if they signed out.
In the movie, the officer signs out and leaves the gates to catch a cab. Then, somebody in the camp yells to him that he’s left his jacket, so he runs back in, signs back in, and gets his jacket. Then he walks back out and the Irish guards don’t catch it.
Technically, he’s under no honorable obligation to return because he didn’t sign out. He’s legally “escaped”. In the movie, he returns to London and the Brit government agrees to return him to the camp.
When I saw the movie, I thought it was just Hollywood BS, but was very surprised when I did some research.
Typically military. The BS is real and the real BS. ;-)
And maybe the Irish guards didn't care.