In Swaledale, Yorkshire, the site of an abandoned Romano-British settlement was named in a twelfth-century monastery charter (1185 x 1191) as Stainburghanes. The site was later enclosed as a pasture and since a record of 1844 it has been a walled field called Brown Close. There are no name records between these dates. Helpfully, another settlement in Swaledale named in 1561 as Borwayns is almost certainly the farmstead known since 1844 as Brownberry, located on the edge of Brownsey Moor.
I understand the root of -burghanes and Borwayns must be the postulated Old English burgæsn, burgæns ‘burial ground’. Across the northern counties there are dozens of such place-names, mostly fieldnames, and many survive in forms like Berwens, Burwain and Barwens (Cavill 2018, 30).
Can anyone point me to the literature that explains (hopefully as far as possible in layman’s terms) how the w entered the word? And does anyone know of any other examples where the modern iteration has become, presumably by metathesis, Brown? Any help will be much appreciated.