Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.
FALLOON
As described in historical dictionaries
Patronymica Britannica (1860)
FALLOON. Trobably a Walloon, or native of what was former)' called the Spanish Netherlands. The Walloon laugnage was said to be a relic of the ancient Gaulish, and hence the people of Artois, Hainault, Namur, Liixenibonrg, and part of Flanders and Brabant, who spoke it, were called Walloons or Gauls. The substitution of F or V for W is very natural. See, however, O'Fallon in this Supplement.