Lately I've been listening a lot to Hootenanny Singers. In spite of the name their thing was singing sugary harmonies of Swedish standards. Their heyday would have been when I was very small, so I don't consciously remember having heard them, yet they are well familiar, so I must have heard others hum the songs they had on Svensktoppen for weeks and weeks at the time.
Now I found a very rare piece, the Russian song Катюша performed in Finnish by the Hootenanny Singers, and while they're doing their best they have an utterly cute Swedish accent. :-)