Russell, Bloodline: The Celtic Kings of Roman Britain

All this may really show is that either the Latinisation of Celtic forms did not follow a set path or that the inscription cutter was used to the spoken, rather than the written, version of the tribe and town and that no one really cared all that much. Today, the names that we give to people and places tend to be rather fixed, but such things were certainly more fluid in the distant past. One has, for example, only to think of the many variant forms of surname provided for that the great Elizabethan poet and playwright Shakespeare (Shake-speare / Shakspeare / Shakespere / Shakespear / Shackspeare / Shakspere / Shakspear / Shak-speare / Shakespheare / Shaxspere and so on) to realise that rigidity and certainty in spelling is a curiously modern obsession