Watch Sangeeta's interview with Earl Spencer.
It's been described as a neglected period of history that changed the face of the monarchy but the brother of the late Princess of Wales, Charles Spencer, is determined to change that.
Earl Spencer has written a book retelling the story of the White Ship which sank in 1120 killing William the Conquerer's grandson as it returned triumphantly from a battle in France. It left the then King - Henry 1st- without a legitimate heir to the throne.
The medieval tragedy led to a civil war and has many connections to our part of the world.
Watch clips from the expedition to find the ship here: