The Ovaltine carol - source?

Posted by Keith Rennie on December 13, 2004

Uncle Bill and Aunty Mabel
Fainted at the breakfast table.
Let this be an awful warning
For those who do it in the morning.

But OVALTINE has set them right
Now they do it every night.
Hark the Herald Angels Sing
Ovaltine's a damn good thing.

Not quite a phrase, but what the hell, it's Christmas.
cited from (slightly senile) memory.

Source? I seem to think John Le Carré but surely there is better authority. Did it ever really exist or did he make it up from whole cloth?

- have a very festive season folks. Morning noon and night.