Andrewartha and Trewartha are Cornish family names.
"Cornish names" says:
Nouns:
"tre" a "town", feminine, maybe a hamlet or house
"tref : village, town", Brythonic Celt Welsh about 4-500 AD
Adjectives:
"Wartha" : "upper" (maybe higher or greater or on a hill)
cf. "Wollas" : "lower" (maybe smaller or lesser or in a valley, of the two).
Definite article:
"An" used as : "of the", "in the", "on the", "at the", in place names. Brythonic Celt Cornish language (Dexter, p. 18).
The book mentions "Trewartha" (p. 25), and "Andrewartha" (p. 60).
The "Handbook of Cornish Names" states: "Trewartha" is a Cornish name meaning "Upper Farm" or "Upper Homestead".
