The first is that it comes from the original London cast recording of the musical, Oliver!, Lionel Bart, and it's probably unknown to most people. It was in the show when it came to America, as far as I know, but wasn't recorded for the cast album. And later, when they made the Oscar-winning film, the song was cut from that. So, it's likely that many people who think they know the score to OliverI -- don't.
The song is "That's Your Funeral," sung by Mr. Sowerbury the undertaker when Mr. Bumble comes by to sell young Oliver to him and his wife.
And that leads to the second reason. The actor who played Mr. Sowerbury in that original production was an Australian named Barry Humphries. Some of you may recognize the name, but most won't. But many do know him -- just in another guise.
That's because, you see, Barry Humphries went on a few years later to create another character that he's been playing for half a century. Dame Edna Everage. Humphries has announced (again) that this current tour of Dame Edna's will be his last. He's said that before, though at 80 years old now, that might be the case. We'll see.
But before that, before even Dame Edna, here is Barry Humphries as 'Mr. Sowerbury' singing the song you don't know from the original production of Oliver!, "That's Your Funeral".