There was a question about sources for large, Tolkienesque elves in Celtic
In _The Fairy-Faith in Celtic Countries_, WY Evans-Wentz quotes on pg.62
(1966 University Books edition) "an Irish mystic who is a seer" as speaking
of the Sidhe so:
Stature of the "Sidhe."--
Q.--You speak of the opalescent beings as great beings; what stature do you
assign to them, and to the shining beings?
A.--'The opalescent beings seem to be about fourteen feet in stature, though
I do not know why I attribute to them such definite height, since I had
nothing to compare them with; but I have always considered them as much
taller than our race. The shining beings seem to be about our own stature or
just a little taller. Peasant and other Irish seers do not usually speak of
the Sidhe as being little, but as being tall: an old schoolmaster in the West
of Ireland described them to me from his own visions as tall beautiful
people, and he used some Gaelic words, which I took as meaning that they were
shining with every color.'
So clearly there is a precedent for tall elves in Irish lore as well as
Hope this helps!