Interesting email from an Irish fellow about Irish kilts.

[O'Callaghan]

I would say that Gunn hasn't changed at all, accidentally or otherwise. According to all reputable sources, Gunn is always a Highland surname, ultimately of Norse origin. The Irish Gunns would simply be descendants of Highlanders.

McGrath and MacRae (or Magrath, McGraw, etc.,) are all Anglicisations of the Gaelic Mac Raith (earlier Irish Mag Raith) meaning 'son of Rath'. For some reason, this is often rendered as Mac Craith in Modern Irish. If Gaelic mythology is any clue, it would appear that Rath was a very common personal name in ancient times. Several unrelated clans in both Scotland and Ireland could have risen and fallen over the centuries, with their descendants today lumped into one or two groups.

The Maccraith that founded the Irish MacGraths was not the son of a Rath or Raith or anything like that according the old lineages, FWIW.

"In Kerry, the following have been the chief Anglo-Norman and English families:--Fitzmaurice, earls of Kerry, descended from Raymond le Gros, a celebrated warrior who came over with Strongbow. Raymond having formed an alliance with Dermot MacCarthy, King of Desmond, got large grants of land in Kerry, in the territory called Lixnaw. The other principal families were those of Herbert, Brown, Stack, Blennerhasset, Crosbie, Denny, Gunn, Godfrey, Morris, Rice, Spring, etc."

http://www.libraryireland.com/Pedigrees1/Desmond.php