Is this what you're after? this is the music hall version:

A mother was washing her baby one night
The youngest of twelve and a delicate mite

The mother was poor and the baby was thin
He was nowt but a Skellington covered in ski-in

The mother turned round for the soap off the rack
She was only a moment but when she turned back

Her baby had gorn, and in anguish she cried
"Oh where has my baby gorn?" The Angels repli-hied

Your baby has gone down the plug hole
Your baby has gone down the plug

The poor little thing was so skinny and thin
He should have been washed in a jug

Your baby is perfickly happy
He won't need a bath any more

He'a splashing about with the angels above
Not lost but gone before