I must confess to being Australian, Brenda, though my grandparents migrated from England at the turn of last century from England.My aunt, who came with them at the age of 3 months is still alive and has not become naturalised despite living here for virtually all of her long life.Our ancestral home was in Ashby de la Zouche, recently revealed as also the seat of the true Plantagenet line of Lord Hastings.
Sir Gideon Isom / Ison / Isham b 1650, Shropshire - d Xmas eve 1701, Ireland is listed as having a son, Sir John Isom / Ison, b 1685-9, England, married Martha Elizabeth Huff, c1676, England, d 1759 in Virginia.
Hope this helps confuse you more, as it does the rest of us.
I suspect that Ison is one of those names that has suffered from convergent and divergent evolution for some time.It has always been a family name with a peculiar feel to it.Theories of Scandinavian origin would have us believe that the -son ending indicates this, and it may well have been misunderstood as such at Eric Bloodaxe's court.As I have controversially stated elsewhere, I believe it to be Greco-Egyptian and to mean Jesus the Great.
I know of a branch in Australia that changed their name to Myson.