I’m a huge fan of royal history, I read anything about it so I was momentarily confused whilst reading an article on Edward III of England, surely he should be Edward IV since The Confessor pre-dates the Edwards I-III by about 311 years (not sure if I’m using the right maths, I just calculated the years between the death of the Confessor and Edward III, which is the period of 1066-1377) and yet he’s not known as Edward I “the Confessor” or whatever order it’d be in. Is there a reason for this?
P.S. I chose not to count Edward the Elder since it isn’t really until his son Æthelstan that we get the King of England title as we know it (as in the actual title name) but I could be wrong to discount him?
There's no great, detailed and complicated answer to this. Only the kings post-1066 get counted. This was engrained in the way medieval documents were dated, and we've kept it because changing it now would be a pointless hassle.
A lot of medieval documents, especially documents produced by the government or relating to their business (ie tax documentation), were dated according to the regnal year. To pluck an example from my 'Latin for Medievalists' exam:
'Dies Lune proximo ante translacionem Sancti Edwardi regis et confessoris anno regni regis Ricardi secundi post conquestum undecimo.'
Which means:
'The Monday before the translation of Saint Edward king and confessor in the 10th year of the reign of king Richard the second after the conquest'
Medieval administrators weren't really sure what counted as a 'king of England' before the Normans conquered everything (and modern historians are still a bit unsure who exactly gets to be called the first king of England), so they just started counting from afterwards. The practical needs of dating official documents is also how the regnal numbering system got started in England. They often designated kings as 'William, son of William' (William II) or 'Henry, son of John' (Henry III) to denote the king, though there were some exceptions. This got awkward when there were 3 Edwards in a row and this convention could not be used, as it failed to distinguish between the second and third Edwards (both being sons of Edwards), so they just started numbering them. Even this became impractical when the Wars of the Roses kicked off, and that's when they just started writing the date like we do today.