This movie is about my age...we both came out in 1954.
It was the height of the cold war, and the possibility of mutual annihilation by the West and East was there. It would not be laid to rest until it nearly culminated eight years later with the mushroom clouds of the Cuban Missile Crisis. And shortly after that came the ultimate "black comedy" about the period, "Dr. Strangelove". But this film came earlier, in a slightly more hopeful period. Stalin had died a year before, so the Soviet Union looked a little less threatening. Not much, but a little. The invasion of Hungary and the crushing of its revolution in 1956 ended that image.
The hope in this film is based on one concept - suppose the Russians suddenly believed that their missiles were worthless due to some new weapon. In this film it is a device that looks like a tricycle with three brass balls connected by a broken umbrella frame. Actually it is precisely that - a piece of junk thrown together by two sailors as part of a lark, and attached to their warship. Naturally it excites the interest of the Russians. It also intrigues Akim Tamiroff, the President of the country that the British warship is visiting. He manages to purloin it (the sailors can't do much about it - after all it is not actually real naval equipment). Tamiroff is afraid that a Russian backed neighboring country may take over his because of their missiles. His country has none. He does have Martin Miller, a kindly, eccentric physicist who examines the device and pronounces it useless. But he and Tamiroff note the Russian interest in it - and decide to take advantage of it. And by a skillful bit of a scam, they convince the Russians and the neighboring country that atomic missiles are useless against the new device.
It is a charming little comedy, with bits of in-jokes (Tamiroff and Miller begin a conversation with the former saying, "Since you don't understand my language, we'll communicate in pidgin English."). It should be revived, to remind us of what we feared the most, and what we wished to end as though it were all a bad dream.