In black and white, and dating from 1960, this movie is (even) older than I am. A British army colonel, bitter at being made "redundant" after a long and successful career, recruits a group of former army officers, all of whom have criminal records. He proposes that they rob a bank - but with the precision and timing of a good military operation. He's already done much of the planning, but there's still training and the illicit acquiring of needed equipment to be carried out.
I found the carefully detailed and rather sordid history of the individual men to be significantly at odds with the way the movie shows them as rather charming Gentlemen. But mostly the movie is fun to watch, a passable heist movie. However, at over 50 years in age, I suspect most people would be just as happy watching something new that's not quite as good because this just isn't good enough to be a "classic."
SPOILER ALERT: I'm going to talk about the ending - that is, if you're concerned about the ending of a 56 year old movie.
It wasn't the Hayes Code that caused them to write the ending provided because this was a British movie from end to end, and the Hayes Code is American. But I heard - I think in commentary on some other movie - that back then, the movie industry required that criminals not be seen to profit from crime. And thus, after an essentially perfectly executed heist, our protagonists (for they're hardly "heroes") are caught anyway. It felt like a bit of a let-down.