i remember a tv play that deeply affected me from the 1970s.it starred peter arne as a man obsessed with catching a white horse on dartmoor with a rope lassoo.theres no dialogue and after days of stalking he almost gives up but then at a pool the horse lets him stroke it,he jumps on and has an icredible gallop over the moor.anyone else remember this play,what it was called and if its still available?