Does anyone remember this book? It's name evades me and I'm really interested to read/watch again.
I think it was written in the 60s or 70s and I read it during primary school (aged 10 or so), it's set in England and is about a man who returns to the family to claim a stake in a rather wealthy. He was a twin who "disappeared" aged 7 - but the other twin knows it's not him, because he in fact murdered the twin and hid the body in a cave on the property - so of course can't come clean about how he knows it's an imposter.
It was adapted for British TV and I remember a scene where a woman is galloping her horse to jump a fence and on the other side of the fence, pegs have been hammered in to the ground.