This is a response to an old question but should put it all to rest.
Leofric was the Earl of Mercia who married Lady Godiva, as noted by an earlier thread.
His son was Aelfgar, Earl of Mercia.
His son was Edwin, Earl of Mercia. Edwin died in 1075 and the earldom of Mercia was discontinued at that time.
Estmond therefore could not have been an Earl of Mercia since he was born about 1074 and the earldom was discontinued at the death of Edwin.
See any encyclopedia (such as Wikipedia) for confirmation.
In summary, Estmond, who was apparently a son of Eadnoth "the Staller" a marshall of the king, was never an Earl of Mercia or anywhere else.
And finally, the name "Godiva of Normandy" is at best a misnomer, since Godiva is an Anglicization of Godifu, a Saxon name and not a Norman name.
My suspicion is that some over zealous hobbiest "created" this couple to get from one generation to another. Unfortunately even if Godiva existed (I can find no evidence of that) she could not have been the sister of WTC, being a generation younger at least.
We should all agree once and for all that Estmond, son of Eadnoth (maybe) had a wife unknown.
And then there is the very real question: Is Estmond a figment of imagination as well?
Although well attested on the net (through copying over and over) no evidence has been found by me that he even existed, and certainly not in any "royal" capacity.
I hope this finally dispenses with this sad issue.