Gorgeous, isn't it? It's easy to forget what a glorious voice Robert Plant had. Noisy and filled with the blues. I forgot his birthday a couple of days ago too. Happy Birthday Robert.
Argenteum Astrum, the premiere bootleg listing, says this is from a boot called "Differently Mixed Coda",
Edit: Commenter Zepette says, "This actually isn't a Led Zeppelin tune, but a Robert Plant and Alexis Korner song recorded prior to Zeppelin. The song is called "operator" and can be found on Alexis Korner's album : "bootleg him". Planty was but a teenager when this was recorded."
Thank you. It's also on Robert Plant's album "sixty six to timbuktu".