This is a question my mother asked me and I wasn't able to answer. She is trying to identify a short story she read as a girl. It would have been written in the 1950s or earlier, and almost certainly by a British author.
An explorer is exploring a desolate world (possibly a future Earth) and finds humans reduced to a hunter gatherer existence. They sing a song that the explorer eventually realises is a corrupted version of George Formby's hit Bless 'Em All.
I have ransacked my collection trying to find this but without success. Googling has found me just one reference here:
There's a rather touching science fiction story of about twenty years ago which recounted a future anthropologist lost among savages in the future Britain. He hears a strange garbled song which goes:
Bina mosha sada rosha
And, as he dies of wounds at the end of the story he makes the connection between the devolved residents and their song.
This plot device of a popular song corrupted by time is tantalisingly familiar, but I cannot pin down the memory. Of course it's possible the device has been used more than once and I'm dimly remembering some unrelated story. If anyone can identify the story I and my mother would be most grateful.