Robertson
Robertson—This name is the anglicised form of Mac Donnchaidh of the Clann Donnchadha in Perthshire. There are several other anglicised forms of the name, amongst which are M'Donochie and M'Conachie.
Alphabetical Index of Anglicised Surnames in Ireland
See also Woulfe’s Irish Names and Surnames
… and O'Hart's Irish Pedigrees