It is a song popularized by British singer Vera Lynn during the dark days of WWII. https://www.youtube.com/watch?v=dTWy9jim7Mw It is perhaps an appropriate song for people dealing with our present pandemic.
"Noel [Coward] and I were in Paris once. Adjoining rooms, of course. One night, I felt mischievous, so I knocked on Noel's door, and he asked, 'Who is it?' I lowered my voice and said 'Hotel detective. Have you got a gentleman in your room?' He answered, 'Just a minute, I'll ask him.'" (Beatrice Lillie)
It can be such a tearjerker of a song, implying a reunion in death, or it can be a happy, hopeful toe-tapper looking forward to better days.
My favorite recording of the song is actually both: it was Johnny Cash’s last song released before his death, featuring a chorus of close friends and family members. Cash was close to death and the song was his goodbye, but he was also a devout Christian with a lifelong sense of humor, so he chose to do an upbeat, cheerful version of the song instead of a ballad reading. It’s almost got an “Always Look on the Bright Side of Life” feel to it. Given how much of his final album series revolves around death, fear and mourning, it seems Cash preferred to go with a wink and a smile.
Oh my gosh! I went to a camp where we would sing at meals, and a lot of the tunes were from well known songs. There was a song we sang (well, not so much when I went there, but I know it) that was to this tune!! Love it!