MacCallum Malcolm Regional Concentrations
I came across an interesting web site recently. Probably, you are familiar with it. It’s the National Trust http://www.nationaltrustnames.org.uk/ that allows you to do a surname search in the United Kingdom. It provides searches in years 1881 and 1998 showing regional concentrations of the surname. What I found interesting was the significant difference in searching for the surname MacCallum and Malcolm. Malcolm shows a further northern and eastern orientation compared to the MacCallum name which shows a western central concentration. Notwithstanding, Chief Dugald’s name change in 1779 from MacCallum to Malcolm there must have been a significant group of Malcolms in the eastern Highlands. Does any Malcolms of the clan have an ancestral connection to the north eastern highlands region?

Concentration of surnames
I'm James Malcolm, originally from Fife - now living in Kilmartin, near Poltalloch estate. I've recently traced my ancestry back to 1745 in the area of Kinross/Clackmannan. Reasearch has shown clusters of Malcolms in Angus (NE), Perth, N. Fife, Kinross, Stirling and Dunbartonshire. My theory is that the name could be occupational (like Smith or Cooper). It derives from Mael Colum or disciple (follower) of St Columba and could have been used to identify an individual who was a priest of the Columbian church (pre 11th century). Thus several, unrelated families went under the name of Malcolm in areas which were the centres of the church. Any further ideas?
Concentrations of Surnames
I'm Dianne Malcolm. My dad was born in Wick, Caithness. I have traced my ancestry on the Malcolms back to 1750 so far and all are predominantly Wick but also other areas of Caithness and possibly Orkney. Malcolm was a fairly common name in this area. My understanding is the same as yours in that it originated from those who followed St Columba.
Followers of St. Columba
Thanks Dianne and Jim for your comments. Granted our surname translate to a follower of St. Columba but why such a high concentration in this area? Another variable for me is that DNA results show my halotype originated in NW Ireland. There is a significant grouping of individuals now with this halotype both in nothern Ireland and in the western mid section of Scotland or the Old Dal Riata Kingdom, right smack in the Poltalloch area and eastwards.