We need the gossip the Royal Family generates just to remind us how the other one-tenth lives. The rules and conventions by which the upper class regulate sex are, for the most part, a mystery to those of us with bourgeois assumptions that permissiveness was invented in the Sixties and that monogamy is still the best policy, unless, say, you're French. So let us be grateful when someone lifts a heavy curtain on what goes on in stately bedrooms.

I caught a bit of High Society the other night on TCM and enjoyed Seth Lord - the millionaire with the wandering eye “and foot” - explaining to his daughter, Tracy, how philandering “even of the most innocuous type such as mine” does not interfere with marital fidelity. In the same vein, Julian Fellowes's Snobs, set among our own country estates, is a terrifying novel about what happens to a young woman who transgresses the uppers' strict codes of adultery.

The story of Prince Charles's Other Mistress, Dale Tryon, had a similarly sad moral. Dale, who bounced into the Prince of Wales's bed in 1974, was never going to have a chance understanding all the nuances. As her nickname, Kanga, implied, she was Australian and the rules are different down there. She quickly, mind you, adapted to one local custom on arrival in Britain. As a married woman, it is not done to have it off with other men until you have first provided your husband with a male heir. Having taken advantage of Camilla Parker Bowles's confinement to start her affair with Charles, she played by the book after she married a stuffed-shirt aristo named Anthony Tryon. By the time she had sprogged, Camilla was back on the scene. Fortunately, Camilla conveniently then got preggers again. As Kanga's tittle-tattling confidant Christopher Wilson explained of Charles's two mistresses, when one got pregnant he would go to another.

Even Charles's hypocritical marriage to Diana did not deter him or her. Instead, she cosied up to the Princess and formed an alliance against the “real” enemy, Camilla. At Live Aid, Diana pointedly wore one of Kanga's dresses (she had opened a clothes shop in Knightsbridge). What did for Kanga was that she did not understand that she had to keep her Aussie trap shut. Her pathological need to phone Nigel Dempster on the Mail was particularly frowned upon. By the time Diana was off the scene so was she: Camilla got her clear run to the British throne.

By now Kanga was ill, physically with cancer and a recrudescence of her childhood spina bifida, and mentally. She jumped from a rehab clinic window and broke her back. Her friend, the mad-looking actress Sarah Miles, vividly described her cocooned in bandages from which her frightened face peaked out and whispered the lie “I was pushed”. Paraplegic and paranoid, she died in 1997 two months after Diana, another woman driven to the verge of insanity by our coming King who did not, obviously, attend her funeral.

You might say that rehashing all this in the run-up to Charles's 60th birthday is in the worst possible taste. But that only means you didn't catch last night's Conversations with a Serial Killer. Here an ex-cop turned schmuck, I mean psychic, called Bobby Marchesso wandered around the old haunts, and I do mean haunts, of the Seventies serial killer Ted Bundy, who murdered long-haired brunettes. Marchesso, as he retraced Bundy's peregrinations, reported changes in room temperature, energy orbs on his photos (dust specs to the rest of us) and that his video camera kept turning off. Jeeps! Ted, fried by the state in 1989, was still with us!

In a séance held in an old boarding house used by Bundy, Marchesso rather half-heartedly affected to be possessed and muttered to a brunette at the table: “It could have been you.” He later said he could not apologise enough to her, although whether this was for his antics or Bundy's was not clear. Marchesso told his pretty pretend-sceptic sidekick Julie MacDonald, an “investigative journalist” who had taken the precaution of being blonde, that he felt nauseous (“naw-shuss”). So did I. That said, the programme was more competently directed than many its dubious genre.

You have to wonder, though, about people who waste their time watching this sick make-believe when there are real and fascinating mysteries to relish. Nature Shock related a cracker of a biological detective story about an outbreak of tumours among Tasmanian Devils. Among the alarming aspects of the disease is that it is the first fatal contagious cancer. The programme explained what was being done to save what is left of the species by breeding a new generation of cancer-resistant devils. It's nice to know that the Devils, unlike Kanga, another Australian native less dangerous than she was painted, are able to be rescued in their hour of need.

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