Sigen married Ughtred "the Bold" FITZ WALTHEOF Earl of Northumbria, son of Waltheof "Siward", Earl of Northumbria, and Elfeda. (Ughtred "the Bold" FITZ WALTHEOF died in 1016.)
Simeon of Durham's Account of the Siege of Durham records the marriage of "Cospatric's son…Ucthred" (although from the context "Cospatric" appears to be an error for "Waltheof") and ... "the daughter of a rich citizen…Styr the son of Ulf…Sigen". 1
1 Foundation for Medieval Genealogy, Medlands: Uhtred.