Hi... my Scots Kith & Kin bbok advises that Thompson is the same as Thomson and originates from Ayrshire 14th Century of the Clan MacThomas. This clan was founded by Thomas, a natural son of Angus, sixth chief of Clan MacIntosh in the 14th century. A Clan MacThomas appears in the list of Clans belonging to the Ancient Federation of Clan Chattan. In a later role (1587) there occurs Clan MacThomas in Glenshee: Hope this is of assistance to you. Best Wishes Jill Van Der Reyden