I would say Thurston too. A Sarah Elder married a Thomas Miller 17/12/1750 Suffolk (familysearch) - no actual place shown but FindMyPast has the marriage from Boyds Index and this states the marriage took place at Thurston.
So, definitely Elder's in the parish at the time - as no other children born to George and Sarah there I wonder if he died and his wife remarried (or indeed it may have been a sister of his).
Annette