Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.
PUREFOY
As described in historical dictionaries
Patronymica Britannica (1860)
PUREFOY. O.Fr. pure foy, literally " pure faith." Originally applied to a faithful ally or follower. The family M'ere seated at Misterton, co. Leicester, in 1277. The motto borne by one branch is " Pure () est ma joie."