As far as I am aware, Action has never been recorded in a studio.
I do not consider the BBC radio 1 version or the Studio In Session version a 'proper' release.
I would love to hear a recording of this song professionally produced and mastered.
That's what I meant by unreleased.
From this list, I went with "I'm Playing Easy to Get"
Not sure why "It's hard to Walk Tall When You're Small" is on this list. The song was officially released. Just about every song has an "early version" to it, and many have leaked. A lot are somewhat/significantly different. Once a song is officially released, that version trumps the others, at least insofar as the topic of this poll is concerned.
Otherwise I'd say that the early, heavier version of "Why Don't you Find Out for Yourself" should be on this list.