Among the most informative of sources available from which to extract information about births, deaths and marriages, with other essential information, are County or Parish Registers that go back to 1538, though their accuracy is often open to debate.
The accuracy of the entry might not however always be credited to the skill of the recorder; if that person to whom the entry referred was illiterate and could not provide the accurate spelling of his or her own name, then the recorder would use his own judgement and make the entry, as he believed it to be.
Such anomalies creep many times into the history of just one family, well explains the changes one often finds to the surname of today's descendants from those whose records were entered centuries before.