http://www.mids.org/sinclair/history/med/battleofhastings.html
Professor Philippe Champy (with whom I have had a lengthy corespondence) does not think that Walderne, Hamon and Hubert were brothers but he has failed to convince me on this point. Hubert may have had a different mother which may have accounted for his decision to side with William rather than with Walderne at Val-es-Dunes. Mothers exert great influence. There may have been sibling jealousy (again prompted by the mothers) and, as Hubert would never have been Duke of Normandy (whoever won the battle) he may have decided to ensure that his sibling rival, Walderne, didn't get it..... so he supported 'the Bastard'. If the Battle of Val-es-Dunes had swung the other way (and it was a closely run thing) the Sinclairs would have become the Royal Family of England and eventually of quarter of the World. If that had been so, would there have been a Boston tea-party? I doubt it! There would have been a Northern Commonwealth of Nations as had been envisaged by Prince Henry Sinclair and Queen Margrette of Norway as early as the end of the 14th Century when trade across the Atlantic was already taking place on a considerable scale.

English Sinclairs / 9 companions of William the Conqueror
From: "Richard Lower" <coqnord@goldstate.net>
Date: Fri, 18 Jun 1999 11:26:48 -0700
Dear Donald: Andrew Sinclair says they were: Hubert Sinclair, Earl of Rye, and four of his sons, Radulph, Hubert, Adam and Eudo. Walderne, Earl of St Clare with his three sons, Richard, Britel and William. He adds the Earl of Senlis, then notes that "he was a Frenchman and not a Norman" He says that "it is not improbable" that Senlis added his name with his sons on the Roll of De Sancto Claro, but there is no record to support this. Note that Hubert and his sons were Englishmen from East Sussex, while his brother and nephews were Norman. This and much more from Andrew's book The Sinclairs of England.