Why do we call Queen Elizabeth "Elizabeth I" when simply Elizabeth is correct?

• Only second and subsequent English monarchs of a particular name have a number after their name. Elizabeth II, as the second queen named Elizabeth, merits the "II" - but Elizabeth I, as the first one named Elizabeth, would simply have used the style "Elizabeth" (not "Elizabeth I") - so why do we now give her the number 1, and also any other monarchs. EG Henry VIII merited the VIII, but Henry I would have simply been Henry.

• Answer:

  A regnal post-nominal numbers were a Norman (as opposed to English) custom, and it started when Edward I (17 June 1239 – 7 July 1307), popularly known as Longshanks ruled over England. He initially intended to call himself Edward IV, recognising the three Saxon kings of England of that name. However, for unknown reasons, this designation does not appear to have been formally used, the King instead being known as 'King Edward' not only by custom (for a King would generally not be known by his regal designation in ordinary conversation), but in all known formal documentation. Upon the accession of his son, also named Edward, the custom of the old reign was taken as rule "the new King was named Edward II, and the old Edward I. Technically, then, this established the custom of numbering English monarchs only from the Norman Conquest (although Edward is the only name that has been shared by pre- and post-Conquest monarchs).