Mental illness stalked the schedules last night. Well, that's an exaggeration but it will be prowling through this review of the three programmes I saw. The subject is, I was recently reliably told, one of the greatest turn-offs for viewers, so whatever else, the programme-makers must be congratulated for tackling the subject. You will notice, however, that they each supplied a spoonful of sugar to help the medicine go down.

In the case of the documentary about Prince John, the epileptic, possibly autistic youngest son of George V, it was the mystique of royalty. With Nirvana's front man Kurt Cobain's depression, it was the songs that came out of it. As for Horizon, the second part of the experiment in which shrinks had to sort the sane sheep from the unstable goats, it was, let's be frank, the game show element.

Ratings for Prince John: The Windsors' Tragic Secret will have suffered from many viewers' belief that they knew the story, either from a series of press “exclusives” over the past ten years or from Stephen Poliakoff's fine 2003 drama, The Lost Prince. We sort of know the story of the boy the Royal Family abandoned to his nanny and a village on the outer reaches of the Sandringham Estate. Rarely visited, he died of an epileptic fit aged 13 before rumours could get out that Mad King George's genes had resurfaced. Paul Tilzey's film had only one way to go: to insist that the tragic secret was less tragic and less secret than we thought. This was an unusual case of a positive revisionism.

His scoop was to find a very old lady, Elsie Hollingsworth, who had actually been the Prince's friend. Queen Mary had taken the trouble to find her little boy playmates from the families of estate workers and Elsie, the coachman's daughter, was one of them. Elsie remembered him as a happy boy. “We understood he was slow and backward so we helped him do things. Once he climbed up a window cleaner's ladder. He thought it was very funny.” She also remembered the Prince frequently being taken up to Sandringham to see his family.

Poliakoff cast an interesting child actor, Matthew Thomas, as the Prince and from that we probably think of him as clumsily big. Yet self-portraits that John sent to Elsie show him normal sized and rather beguiling. But otherwise, Poliakoff, who was interviewed for last night's programme, provided a sympathetic view of the situation, arguing that the Prince was “free” in a way the other members of the Royal Family and their servants were not. If there is a villain in the story, it is the ghastly Edward, Prince of Wales, who wrote to his mistress of his brother's death that to “plunge into mourning for this is the limit”. Tilzey's film was touching: people are sometimes kinder than they are given credit.

Mental incapacity, obviously, was not the brilliant songwriter Kurt Cobain's problem, but depression was. Kurt Cobain: About a Son simply played us tapes of interviews conducted by his official biographer Michael Azerrad about a year before Cobain apparently shot himself in the head. Mostly recorded in Cobain's house in Seattle between midnight and dawn, the monologues recalled the worst wee-hour whinings of first-year students. Cobain had felt so alienated as a child that he thought he was an alien. His father placed him bottom of his to-do list. His fellow students were “carbon copy idiots” or else “sub-average geeks”. Working in an hotel, he was workshy not because of the work but because of his co-workers: “I cannot get on with average people.”

On and on he moaned, for 97 minutes, as the director A.J. Schnack illustrated these sub-thoughts with rather beautiful images from Cobain's perfectly harmless hometowns of Aberdeen and then the Olympic Peninsula, to which he moved, and Seattle. There was, naturally, great poignancy in his unfulfilled threat to stay alive “just to spite those f***heads” in the press, but, did one not know his music, one would agree with the self-assessment with which the film opened: “My life is so f***ing boring. We don't deserve to have a book written about us.”

Horizon wrapped up two weeks convincing us that mental illness occupies just part of a continuum between normal and full blown insanity. Its technique was to give three shrinks the impossible task of separating five people recovering from mental illness from five who had never been troubled by it. They spotted two, the obsessive compulsive and the ex-anorexic, and misidentified a mildly eccentric Scot called Vicky as a possible schizophrenic. That diagnosis is, said one of the panel, the psychiatrist's equivalent of telling someone he or she has cancer. Fortunately, they avoided actually using the “s” word to her. This was as well, since none of the group had, it turned out, ever actually been schizophrenic. This was just another flaw in a deeply unsatisfactory experiment.

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