Everyone knows you're not supposed to talk to anyone on the London underground, but there are exceptions – such as when an impromptu singalong begins on the platform after a gig.
The original version of the singalong, uploaded to Facebook, has been watched almost half a million times.
Francis, 47, told the Evening Standard: "I was surprised and also not surprised."
"The majority of people at the station had come from the concert but what is really surprising is the way the video has suddenly gone viral.
"I have had some absolutely amazing comments from people all over the world who I do not even know."