This is Estrith, the sister of King Canute, and daughter of
Svein, King of Denmark. Sources claim that she married Robert,
Duke of Normandy, but it is difficult to work this out,
chronologically, and some have tried moving her to his father,
Richard II, but unconvincingly.
taf
The earliest author, Raoul the Bald (writing in 1040s), clearly
indicates that Canute's sister married duke Robert (who died in
Nicaea) who soon divorced her and had a son by concubine, so this son
recieved his ancestor's name, William.
Adam of Bremen (whose information on Norman affairs is often insecure)
confused Robert with his father or brother: Count Richard, fleeing
Canute's anger, withdrew to Jerusalem and died here... To make peace
with Canute, who had captured his sister Emma, he had to marry
Canute's sister Margaret... ("Chnud regnum Adelradi accepit uxoremque
eius Immam nomine, quae fuit soror comitis Nortmannorum Rikardi... Et
Richardus quidem comes declinans iram Chnud Iherosolimam profectus
ibidem obiit, relinquens filium in Nortmannia Rodbertum, cuius filius
est iste Willelmus, quem Franci Bastardum vocant".)
There are two Danish sources who used Adam's chronicle and so repeated
his information. The first is Chronikon Roskildense: "Kanutus victor
existens ipsam Ymmam duxit uxorem genuitque ex ea filium Harthe Knut.
Kanutus Richardo suam dedit sororem, nomine Estrith. Que ab illo
repudiata duci Ulf sine fratris consensu est coniuncta". The second
source is Saxo Grammaticus: "Quum Anglorum rebus obtentis nectendam
cum finitimis amicitiam decrevisset, Normanniae praefecti Roberti
filiam Immam matrimonio duxit, eiusque fratri Rikardo sororem
Estritham coniugio potiendam permisit".
regards