I did seek out and watch the original British film a couple of years ago, and of course it IS a classic. Both movies benefit from great acting from all concerned, and both are very funny in their own way. The appeal of the Coen Brothers film for American audiences is that its band of would-be thieves is composed of a number of very recognizable American "types" that would be as out of place in most British films as the cast of the '50s version would be to an American movie comedy today. (You see something similar if you watch the American and British versions of 'Ghosts', and to some extent 'The Office'.) Nevertheless, the '55 British original is most definitely a classic. Many of the British comedies of that era have not aged well.