For background on how the map was made (and its flaws), see the relevant blog entry.
|Mac Tomáis||Thomson: líonmhar: an Dún & rl. Albanaigh arís.|
|Thompson||Very numerous: all areas, especially Ulster, Dublin, South East. One of the most numerous non-indigenous names, usually of English origin.|
|Thomson||numerous: Belfast area, Down etc. Scottish.|
DEDs where Thomson and a second surname are found together