For the moment, set the title aside. There is no character named “Colonel Blimp” in this film—we will come to him later. Instead, our hero, if that’s the word, is Major-General Clive Wynne-Candy (Roger Livesey).
We find him, fat and comfortable, in a Turkish bath. He is a caricature of himself, a grotesque parody of the kind of self-satisfied stiff-upper-lip officer who led the British military into so many ill-advised imperial adventures.
Naked and soft, bald and round, a wild bushy moustache extending forth from his upper lip—the man is the very model of a not-at-all-modern Major General. He is a relic of the turn of the century, a leftover of a British Empire that is rapidly crumbling in the face of Hitler’s relentless onslaught.
The man pointing a gun at the General is the future—young, brash, confident, and willing to “think outside the box” as the saying goes. He is not the General’s enemy—well, not literally, at least. They are both on the same side, and this is but a war game, cooked up as a training exercise in the middle of the real war raging outside. Both men want to defeat Hitler. The difference lies in methods—the old General adheres to a code of conduct and civility from the Old World; the young Lieutenant thinks that in the face of an existential fight against the purest Evil the world has ever seen, no tactics are off the table.
But, in a more metaphorical sense, they are enemies: old versus young, and everything that implies. “You don’t know how I got fat, you don’t know why I grew this moustache, you don’t know anything about my life!” shouts the General—and with that, Powell and Pressburger’s greatest masterpiece unfolds.
To understand quite why this film deserves that emphatic designation “masterpiece”—when there are so many glorious Powell-Pressburger classics from which to choose—we need to take stock of that curious title. As I said, there is no “Colonel Blimp” in the film. So who or what exactly is that title referencing?
A cartoon character, as it happens.
In the 1930s satirical cartoonist David Low started drawing a series of single panel blackout gags involving a small-minded British military officer called Colonel Blimp. The story goes that Low overheard an actual officer sputtering some jingoistic blather and created the cartoon character to lampoon the self-satisfied idiocy of the man.
The cartoons follow a simple a pattern—Blimp, in a towel at a Turkish bath, spouts some racist, imperialistic nonsense like “Gad, sir! Lord Beaverbrook is right—We must refuse to take part in another World War unless arrangements are made to hold it in the British Empire!” and “Gad, sir! We can’t have a colored man here! It would take the minds of resident stinkers off their struggle for the ideals of the British Family of free and equal peoples!” (Yes, the “Gad, sir!” exclamations and the constant invocations of some social authority like “Lord Beaverbrook” were part of the formula).
It was a sensation. Political commentators took to referring to these blinkered ideas as “Blimpy” statements; poor Colonel Blimp entered the dictionary.
Flash forward to 1943, the darkest hours of the war against Nazism. The filmmaking team of Michael Powell and Emeric Pressburger had been making some anti-Nazi thrillers—part action movie, part propaganda. After Contraband and The 49th Parallel, they started work on another film—one that would take a bit of a turn from the predecessors.
In some regards, the new film hit the same propaganda points as their previous works, or the similar work being done by Alfred Hitchcock at the time—an exhortation that the British public needed to rally everything against the existential threat of Nazism, and to understand that the notions of civility and honor meant nothing in the face of a demonic foe that sent children to the gas chamber.
Except… the new film didn’t just stop its argument there, it went on to illustrate how no war is honorable, when you think about it, and that those Old World codes of honor are really fundamentally silly. War is kill or be killed—you either play that game, or you don’t, but you can’t really pretend that doing that is somehow decent.
In other words, a bit of a full-on satirical bodyslam to some of the deeply held principles of Britishness. Which meant dealing with some of the same stereotypes so famously lampooned by Colonel Blimp. Powell and Pressburger licensed the right to invoke the name and spirit of the Blimp character, and then mapped that onto their wholly original creation of Maj. Gen. Wynne-Candy.
Over the epic span of Wynne-Candy’s life we see him clumsily blunder some international relations (by traveling to Berlin to insult a group of German nationalists to their faces, and then act surprised when they take umbrage); fight a duel (pointlessly, and passionlessly, against a man he’d never met); fall in love; marry someone else; do an awful lot of big game hunting (presented as a metaphor for sexual frustration); and grow old into a role as senior military statesman to a military that has little use for his narrow-minded thoughts.
The woman he falls in love with is more of a concept than a person per se. Costar Deborah Kerr plays this paragon of womanhood, but does so by playing several different characters at different points in time—among other things, this conceit spares Miss Kerr from having the wear the old age makeup her costars did.
The man that Wynne-Candy duels is a German officer of similar temperament (Anton Walbrook as Theo Kretschmar-Schuldorff) who becomes his best friend. Through Theo’s perspective we glimpse the rise of Hitler’s Germany—although the film takes extreme pains to insist that Theo is himself no Nazi. Nevertheless, Theo provides a window into the German experience of WWI, bitter defeat and humiliation, economic destruction, and the emotional lifeline that Hitler offered those angry, disaffected souls. More importantly, the film displays those attitudes to us in the audience but Wynne-Candy remains resolutely ignorant of them, unable to read even his own “best friend” even when that best friend unambiguously tells him to his face what he’s feeling.
It was here that the film was veering into very dangerous territory: the British General (whose life story seems to parallel that of Winston Churchill in certain key respects) is a foolish Blimpy type, while the German officer is the reasonable voice of humanity.
The War Office wrote a memo to the producers attempting to convince them to abandon the production; when the film was released the government imposed a ban on its distribution overseas. Right wing groups whipped themselves into a frenzy over the perceived shamefulness of a movie that would dare present a sympathetic presentation of a German character (horrors!)
Ironically, these various complaints were actually mirrored in the film itself—at one point, Gen. Wynne-Candy goes to make a speech on the BBC which is then canceled by the government out of fear that his remarks would undermine the war effort by showing too much sympathy to the Germans and too much Old World insistence on fighting clean.
What hard times those were, when even basic human tolerance and decency were seen as liabilities. Thank goodness we live in a time when this is inconceivable 
The war against Hitler is over, though. And the beautiful power of this movie—and its powerful beauty—is its ability to understand opposing viewpoints. There is nothing Blimpy about the film, despite the resolute Blimpiness of its main character. Instead the movie models how one can understand and even admire people who think differently than you do; how the ones you love need not be people exactly like you. That’s an enduringly necessary message.
For that matter, the Blimpy-esque character of Clive Wynne-Candy is no caricature. He is a lovingly drawn, fully realized character, whose limitations are presented with context and honesty. When we first find him, in full Blimp mode in the Turkish bath in the opening sequence, we are invited to mock him—but over the subsequent 3 hours we see his life with all its warts and all its glory. As the film cycles back to the opening scene, that context has changed our opinion completely—it’s awfully hard to mock him at the end, even if we still think he’s wrong.