Thanks for the help. My own research suggests that the modern name of the hill derived by back formation from the name originally applying only to the earthworks, OE 'werc(e)'. In the tenth century the southern English knew it as 'Brunandune' - Bruna's Hill - but it was better known, at least in the north, as 'Wendune' from Old English 'Wen(ne)' or 'Wenn' meaning a wen or tumour and in place-names used to identify mounds that resembled such a swelling.