Six of these local rulers are for the first time called "comes" in the foundation charter of the monastery of Scone dated [1114/15].
According to Skene, the relationship between these rulers and their provinces was not purely territorial but connected with the tribes which occupied the land.
A more sensible suggestion is that, assuming Magnuss right to Caithness was inherited from his mother, she was related to the last Earl John, who died in 1232, and whose rights would have been divided between his two heiresses.] .
Balfour Pauls Scots Peerage states that William King of Scotland granted lands of "Purin, Ogguluin and Kinminethen" [Powrie, Ogilvie and Kilmundie] all in Forfarshire to "Gilbert son of the Earl of Angus" by charter dated to [1172/77], and that "from him are descended the Ogilvies of that Ilk, Airlie with its cadets, and Inverquharity" ([1175/85]-1239).
A charter dated 1351 which confirmed the donation of "terram de Kenny" to Aberbrothoc by "Walterum filium Turpini" quotes a document witnessed by "Domino Magno filio Comitis Domino Anegus filio Comitis".
He was apparently installed as Earl of (part) Caithness.
No primary source is cited in support of these statements and it is possible that this marriage, and the supposed parentage of the bride, are entirely speculative, in an attempt to explain the transmission of the half of the earldom of Caithness to Earl Magnus (see below).
Skene says that "the probability is that the half of Caithness which belonged to the Angus family was that half possessed by the earls of the line of Erlend, and was given by King Alexander with the title of Earl to Magnus, as the son of one of Earl Harald "Ungi"s sisters" and that "the Norwegian name of Magnus indicates that [Earl Magnus] had a Norwegian mother".
In the 10th century, the title changed to "Mormaer" or Great Maer or Steward.He cites no primary source either, and the implication is that Skene is speculating on all the points which he makes.Concerning the supposed parentage of Earl Magnuss mother, it appears unlikely that Magnuss right to Caithness was derived from the junior branch of the comital family of Orkney/Caithness, to which Erik Slagbrellir belonged, as it ceased to hold any interest in the county after 1198, while Magnuss grant appears to be dated to the 1230s (as discussed more fully below).Balfour Pauls Scots Peerage says that "Magnusis usually designed son of Gillebride Earl of Angus", adding that the "statement was first made by Sir James Dalrymple in his Collections, but he gives no proof".The Complete Peerage says that "it seemsquite probable that [Magnus] was the same person as Malcolm Earl of Angus, son of Duncan, son of Gilchrist, son of Gillbride[who] is named as Earl of Angus and Caithness in 1232 [see above]", although conceding that "the whole matter is, however, very obscure".The Complete Peerage says that Gillbride seems to have married a daughter of Gospatrick Earl of Dunbar but does not specify the primary source on which this is based --- of Caithness, daughter of ERIK Slagbrellir & his wife Ingigerd Kalisdatter.