According to Wikipedia, there is a BBC made-for-TV film called The Happy Valley starring Denholm Elliott and Holly Aird. It's about It is set in the British colony of Kenya in the 1930s, and tells the true story of murder of Josslyn Victor Hay, the 22nd Earl of Erroll, as seen through the eyes of 15 year-old Juanita Carberry, the daughter of John Carberry, a friend of Broughton's. It's never been officially released on DVD and is very hard to find, largely due some rather painful - and apparently delectable, if you're a BDSM type - looking caning scenes. There is another film called White Mischief, which is about the very same subject and is easily and cheaply available on DVD in the UK (it's under a fiver at Sainsbury's Online).