Waltheof's sister Octreda/Ethelreda married Donnchad mac Maíl Coluim, was briefly Queen Consort of Alba, and the mother of William fitz Duncan, mormaer of Moray.[6] After King Donnchad was killed in November 1094 it is likely that Ethelreda and infant William fled Scotland to Allerdale and the safety of her brother's family. William fitz Duncan appears to have inherited Waltheof's Allerdale territory from his mother.[7]
Barrow, G. W. S. (2003), The Kingdom of the Scots: Government, Church and Society from the Eleventh to the Fourteenth Century (2nd ed.), Edinburgh: Edinburgh University Press, ISBN0-7486-1802-3
Hamilton, Elsa (2010), Mighty Subjects: The Dunbar Earls in Scotland, 1072–1289, Edinburgh: Birlinn, ISBN978-1-904607-94-6
Hedley, W. Percy (1968–1970), Northumberland Families, Newcastle-upon-Tyne: The Society of Antiquaries of Newcastle Upon Tyne
Knowles, David; Brooke, C. N. L.; London, C. M, eds. (2001), The Heads of Religious Houses : England and Wales. 1, 940–1216 (2nd ed.), Cambridge: Cambridge University Press, ISBN0-521-80452-3