Don't let's be beastly to the Germans,
You can't deprive a gangster of his gun.
Though they've been naughty to the Czechs and Poles and Dutch,
I can't believe those countries really minded very much.
Noël Coward, among many other successes, had a name for producing popular cabaret songs. These were, generally speaking, quite popular in wartime Britain, his biggest hit being London Pride. Also popular, although rather more controversial, was the song Don't Let's Be Beastly To The Germans, first recorded in 1943. It was intended to be a poke at those few Englishmen who felt that Britain was being too harsh on the Germans, and to modern ears it certainly comes across as satire. Unfortunately, it was not interpreted this way by all listeners.
While it was reported to be a favorite of Winston Churchill -- Coward claimed that Churchill had him play it seven times during a single evening -- there were numerous complaints that it was pro-German, and it was cut from the musical review it was to appear in and banned from BBC radio play. It may be that part of this furor was caused by this also being the first time the word 'bloody' was broadcast on the radio:
Let's soften their defeat again,
And build their bloody fleet again
Regardless, it is a bit of a puzzle how this song was taken to be pro-German, with lines such as "treat the rats with charity", "let the scum rise again", and "they gave us two world wars and Dr. Rudolf Hess". However, there is never any profit in assuming the common man to be attentive or sensible, and Poe's law is not just universal but foundational to human nature.
It is worth noting that "Don't let's be beastly to the poor Germans" had been a popular English catchphrase used since the 1920s, mocking those who would show mercy to the Germans post-WWI. It was fading from use by the time that Mr. Coward revived it, but would certainly have been familiar to his listeners.
A later recording of the song can be found here (YouTube).