In the late 18th Century, 90% of Englishman were called John, Richard, William, Henry, Edward or Charles. Patronyms (or their derivatives) of the first three are common... But where are all the Henrysons, Edwardsons or Charlesons?

Follow-up question: As the English language and cultural identity came together, was the use of "Fitz[Name]" for surnames common, or was it mainly used for families descended from Normans? So if you ran into the FitzHenrys or the FitzCharleses, would you be able to guess with some accuracy if they were of Anglo-Saxon or Norman ancestry?