So, this evening I was sitting in the closet reading Elizabeth Whittingham's THE EVOLUTION OF TOLKIEN'S MYTHOLOGY: A STUDY OF THE HISTORY OF MIDDLE-EARTH, when her third repetition of a phrase made a mental shoe drop. It just goes to show the value of encountering something you already know well out of context (Chesterton's Mooreeffoc).
The passage in question concerned the lesser spirits that accompanied the Valar when they descended into what was later called Arda, the created world. Among others, their numbers are said in THE BOOK OF LOST TALES to include "brownies, fays, pixies, leprawns" (BLT.I.66). These lesser spirits are de-emphasized in the later forms of the mythology, but they never entirely faded away; as late as 1965 JRRT published a stray Bombadil poem (the third featuring that character, by far the best, and the only one omitted from THE ADVENTURES OF TOM BOMBADIL), "Once Upon A Time", which includes the lintips, elusive little creatures even Bombadil doesn't know much about (cf. the far more menacing mewlips of another, much earlier poem). In the end, all these minor Maiar-like folk seem to have been subsumed into the general category 'fay' (which in the early stages of the legendarium is distinct from fairy, the latter then being a synonym for elf).
But I shd have noticed, and drawn attention to, the appearance of brownie here, for the brownies or brown-men of traditional folk-lore are a kind of hob. And, since we have every reason to believe Tolkien drew on hob-lore when creating his hobbits more than a decade later, it's of interest to find a hint of some kind of similar creature within his mythology, albeit in a much different role, at a much earlier stage. I don't think we can make too much of this, but it does at least open the possibility that when Tolkien sat down in the summer of 1930 and spontaneously invented his hobbits he had already potentially made a place for them within his legendarium long before. And we can't rule out that he thought of hobbits along those earlier lines when he first set out to tell Bilbo's story, however greatly they diverged in the telling.
So, if there's ever a second edition of THE HISTORY OF THE HOBBIT, I'll need to add a paragraph or so to that effect drawing attention to this passage to what's now JDR Note 1 on page 850 of RETURN TO BAG-END.