I've posted some information I've found out about Seth Davey and Glyn Hughes on another thread Lyr Req: Whiskey on a Sunday.
The 'facts' about both people are a bit sparse, and sometimes a bit confused. However the Glyn Hughes who wrote the song about Seth Davey died about 1972.
He was a songwriter and guitarist amongst many other roles on the Liverpool scene in the 1960's, and he appears in several accounts of the period. Hughie Jones, Brian Jacques, Jaqui McDonald and many others are all still around from those days and could probably add their memories.

Matthew Edwards