The Love Match by Catherine Fellows

Sara Heywood didn't expect to become an heiress to a large and rambling manor. She just wanted a legacy that would allow her to live in a small village, far away from the damp country she's grown up in. Instead, she is given the house, as long as she lives in it, until she marries. No one else in her family will receive their inheritance either. Her great aunt points out that she could solve everyone's problems by marrying one of her three cousins. It's probable that they (or Sara's brother) might try to knock her off instead as Sara's death would also release the manor. And there are some very suspicious things happening to Sara....
This was more a mystery than a romance (which is the reason I had it on my list in the first place) but entertaining for all of it's brevity. 

Four stars

This book came out in 1976

Hard copy of mine

Opinions are my own