I found the 2 clips I like, already posted back-to-back on YouTube with 63K hits, of course,
Poldark Intro: https://www.youtube.com/watch?v=ZL6vcKNyC7o
Poldark: Demelza sings at Trenworth, https://www.youtube.com/watch?v=ZUT0qBwCXuo

Anne Dudley’s Music for Poldark, http://www.filmmusicsociety.org/news_events/features/2015/072715.html
It’s a hybrid stringed instrument so can play violin & viola, and the album is in Top 10 in Britain, reflecting Cornwall.
Poldark filming locations, http://www.imdb.com/title/tt3636060/locations

Poldark Cornwall