JAGO. " As for the name Jago, wlietlier it be derived from the Celtish-British lago, and signifies .James, or from ijago or jago a spear, or military tuck, I determine not, or from gages and pledges for battle ; however, this uame was of ancient use in Britain ; for Galfridus Monmuthensis tells us of a king named Jago, before Julius Cassar landed in Britain, that reigned twenty-five 3'ears, .and lies buried at York." Hals, in Davies Gilbert's Cornwall, i., 397. The derivation from lago, James (rather Spanish, however, than Celtic); is probably the correct one.

Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.