A quick browse over the names bestowed on the British royal males since the Conquest, shows a boatload of guys named EDWARD, a handful with the name EDMUND (most notably Edmund Crouchback and the brother of Edward IV/Richard III), but only one EDGAR - a son of James II who died in infancy.
I mean, to give you an idea, even when royals started having multiple names, it never made it into the lists. Edward's there. Check for Edmund. But Edgar is absent.
Now, both England and Scotland have had kings named Edgar, yet the name drops from the roll of acceptable names for princes almost as soon as it's included. Why was this? Sheer dumb luck? The fact that there's a St. Edward and a St. Edmund (I think, but the town must be named after him right? Plus there's that church in London that Wren built?) but no St. Edgar? Or were Edgar of England and Edgar of Scotland so bad that they cast a pall over it? Sorta like Richard?
Yeah, I suppose we can ascribe it to sheer dumb luck, I mean, few of the royal names from before the Conquest have been passed on besides Edward - Edmund, Alfred... - we've never seen another Athelstane or Athelred or the like, but it just seems odd.