Last Night's Television - Nature Shock: Mutant Devils, Five; Prince Charles's Other Mistress, Channel 4

Call me paranoid, but I can't help discerning some grim significance in Channel 4's decision to transmit a documentary about the sexual history of the now ageing heir to the throne on the night when our attention is turned to the American presidential elections. To me, what they were saying was, stop getting all excited about the charismatic black guy and change we can believe in – that's over there. Over here, you're still struggling to get out form underneath a quasi-feudal system dominated by wealthy, socially homogeneous, middle-aged and charisma-free men.

Prince Charles's Other Mistress was an account of the life of Dale Tryon, amusingly known, because she came from Australia, as "Kanga" – all right, you can stop laughing now – who for a while in the early 1970s was Charles's mistress and Camilla Parker Bowles's great rival. The relationship died a natural death, helped along by Kanga's habit of relating the details to gossip columnists, but she stayed in royal circles, later becoming friends with Diana, who purportedly saw her as an ally in her battles with Camilla. Kanga had some success with a frock business – Diana wore one of her rather ghastly creations to Live Aid – but suffered ill-health, and after a fall left her paraplegic, she became increasingly mentally ill. At one point, she told her friend, the well-known actress and urine drinker Sarah Miles, that she was about to become Queen of England. She died in 1997 at the age of 49, and "the woman who had once had the world at her feet and the Royal Family in the palm of her hand" was buried at a sparsely attended funeral.

The story was pathetic, in all senses, but hardly enough to sustain attention for an hour, so the programme-makers tried desperately hard to infuse it with glamour and mystery.The moderately attractive Kanga was a "blonde bombshell", Charles "the most intoxicating sex god" of the early 1970s, more desirable than Roger Moore, Tom Jones and George Best, the commentary reckoned, though that claim was sadly undermined by accompanying footage of a sweating, blazer-clad buffoon (I'm not talking about Moore). She was painted as a colonial innocent, whose breezy informality won all hearts, but, a succession of creepy biographers and "confidants" explained, she didn't grasp, as Camilla instinctively did, the unwritten rules of aristocratic sex, which made it OK for her to be shagging the heir to the throne while her husband nipped out for a tactful spot of shooting. Whether, as the programme implied, it takes 300 years of inbreeding to tell you not to go shooting your mouth off to Nigel Dempster is open to debate. Then there were hints of something darker. At the end of 20 years of enmity, the commentary noted, Kanga was dead and Camilla got her man. Later on, this was reformulated: "Two of the three most significant women in Prince Charles's life were now dead, and the way was clear for Camilla." And the fall that paralysed her – apparently a suicide attempt by a woman with serious mental-health problems – was persistently "mysterious". Look, is this a conspiracy theory or not? If you want to say that evil Camilla had her whacked, come right out with it. Otherwise, shut the hell up and let me get on with watching the American election results.

The first thing to say about Nature Shock: Mutant Devils is kudos for the title. Personally, I'm liable to watch anything with either "mutant" or "devil" in the title, and the combination just gives me a warm, tingly feeling. The second is that, after the come-on, the programme exceeded expectations in all respects, being an admirably straightforward and thorough explanation of a fascinating and scary natural phenomenon. In the past 10 years, Tasmanian devils, small but remarkably vicious scavengers, have been dying out in their thousands, killed by a plague of disfiguring facial tumours – we saw horrible photographs of animals with faces swollen and torn beyond recognition. The programme took us through the process by which the plague was spotted and investigated, before it was established that the tumours were contagious; genetically identical cancer cells are transmitted from devil to devil, perhaps through gnawing at the same carcasses, more likely through bites. Devils bite one another a lot, both in frequent fights and during sex. Even if I didn't know that, I don't think I'd be comfortable getting physically involved with somebody with those teeth. The bad news is that, thanks to decades of trapping and poisoning, the devil population has shrunk and become inbred, making it particularly vulnerable to infection; the good news is that a small population of devils in north-western Tasmania has developed immunity.

Every so often, the programme was livened up by somebody proclaiming their love for the devil, or predicting doom for western devils, which made it sound oddly like a tape of Osama bin Laden, and the cherry on top was a narration by Anthony Head, Giles the librarian in Buffy the Vampire Slayer, a man who knows from mutant devils.

Tom Sutcliffe is away