Walk a Crooked Path
Set in an exclusive boy's school, about a man who plans to kill off his wealthy teacher wife by encouraging her to drink and pushing her into suicide. To assist him he recruits a young student who will claim that he was sexually assaulted by her. (from: http://ftvdb.bfi.org.uk/sift/title/390627)
Directors: John Brason
Writers: Barry Perowne
IMDB: tt0195398