Title: Star Creek
Description: Published 1966:  Helen goes to live as a ward of a man who has lost one arm and who is now living in  remote place on the cornish coast. She seems to almost parallel Jane Eyre and also has to deal with smugglers before all comes right.
When Helen's father died, she was grateful to Roger Trelawnce, his old friend and now her guardian, when he offered her a temporary home in his Cornish manor house --and it was not long before she found herself looking on him as much more than a guardian.
But that was before she discovered the existence of Mrs. Valerie Trelawnce.