Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.
GASCOYNE
As described in historical dictionaries
Patronymica Britannica (1860)
GASCOIGNE. GASCOYNE. A native of Gascony, the French province, which being in the possession of England, during a portion of the XIV. cent., supplied this country with many nc-w families and names. See Ducatus Leodiensis, p. ISl, for the twenty spellings of this name. The heads of the family were all Williams, the courageous Chief-Justice who sent Prince Henry to prison being one.