The last comment on that post (by Paul W) said
I'd love to hear more about that discussion on how gnomes became a PC race for D&D.
It's an unfortunate fact that inconclusive researches are harder to sum up that successful ones, but here goes a sort of brief interim report.
(1) for most of the twentieth century 'gnome' seems to have been a generic word very like 'goblin' or 'imp' or 'fairy' or 'elf'. When one did appear, it was generally in a comic context.
(2) the Dutch gnomes of the picture books I posted about a while ago are definitely not the basis of the D&D gnome. They are the inspiration of the Forest Gnome, created by Douglas Niles for PHBR9. THE COMPLETE BOOK OF GNOMES & HALFLINGS (1992),** which I edited.***
(3) there's a long tradition of 'gnome' as a name for humanoid earth elementals, but D&D obviously didn't choose to go that route. Though interestingly enough it has both salamanders (as a non-humanoid fire-creature) and fire elementals, the former poss. inspired by the rampaging salamander in Poul Anderson's OPERATION CHAOS, which I'm currently reading. But the gnome/earth elemental just isn't there in the race's core concept. The xorn or even the umber hulk wd have been closer.
(4) my interim conclusion: gnome was added to the PLAYER'S HANDBOOK player-character races as a token non-Tolkien character. Then anytime someone made the case to Gygax that an awful lot of his game --the player-character races, a third or so of the core monsters, the very concept of a multi-racial multi-class player-character party -- were all borrowed directly from Tolkien, whose works Gygax eventually came to disparage, he cd point to the gnome as non-Tolkienian. And ask Tolkien Enterprises to please not sue him.
In short: I put it on par with 'mithral'. They're not fooling anybody.
(5) my guess: if there is any direct ancestor for the D&D gnome, it's likeliest to be found in UNKNOWN and its descendents/derivatives.
So here's a question I'd like to know the answer to: where does the first gnome NPC appear -- what adventure? And when does the first gnome pre-generated PC see print?
current reading: OPERATION CHAOS by Poul Anderson.
*even using Tolkien's preferred elves over the then-standard elfs and Tolkien's own invention dwarves over the pre-Tolkien universal usage dwarfs. Not to mention Hobbits > Halflings.
**(Pity we didn't port over the cannibal halflings of Athas instead)