”You’re going to Nancy school.”

“You could still be Nancy.” I know it’s pathetic. I know I should have grown out of sniggering at this sort of thing, but I never cease to guffaw when Graham Norton says what they’re looking for is a really big theatrical Nancy who will put bums on seats. And I’m not alone: theatreland is collectively corpsing over the search for Bill Sikes’s girlfriend. I can’t take it seriously. But then I couldn’t take it seriously if they were looking for Norma.

I understand that if you like these lengthy, lachrymose, hysterical indulgences, with their contrived denouements, then I’d Do Anything is fine and dandy. Last week, however, Kevin Spacey complained about the search for... (a pause here for compulsive giggling and a joke about picking up the usual suspects), and he has a point about the BBC producing what, from his side of the box office, looks remarkably like 13 weeks’ free advertising for a competing musical. Theatre producers are right to be aggrieved - doubly so when they are funding their competitors through the licence fee. The point and purpose of these programmes is to market shows that will make a great deal of money, in much the same way pop-singing talent contests are mainly about making Simons Fuller and Cowell richer. The same is true of books. All literary agents will tell you with broad grins that the main cultural purpose, the only cultural purpose, of television is to sell books. You try flogging a cookery book while appearing only in your own kitchen, or writing a travel book that doesn’t involve the number 80 and a 13-part series.

Now, I don’t mind Cowell or Andrew Lloyd Webber getting any richer, and I don’t begrudge Michael Palin or Nigella their positions in the bestseller lists. What I do mind about all this perk-grubbing is the damage it does to the delicate eco-system of the BBC. I am a fundamental defender of the licence fee and public-service broadcasting. It is our most important bit of institutionalised culture. It doesn’t just maintain the corporation, it benefits commercial television and radio and dozens of other cultural events such as the Proms.

The only real defence for the licence fee, however, is that the money is used in ways that commercial companies wouldn’t or couldn’t. And every commercial enterprise the corporation takes part in or is joined to weakens its case for the predicated tax. The commercials on BBC World, the co-production deals with American channels, all confuse and abuse the prime objective of the BBC - the good of the public. Licence-fee payers in Britain are not shareholders in a multinational entertainment corporation. We’re debenture holders. We turn up every night for the show. Profits and power mean nothing to us. We’re interested only in listening and watching.

The BBC was warned about all this when its publishing arm and radio stations took unfair commercial advantage of ads on television. I’d Do Anything is far less defensible. The pockets the BBC is picking, though, are not just Spacey’s but its own. Whether the whole choose-a-star-on-television genre is good for theatre or the long-term careers of the amateurs who take part is another question. It certainly brings in a new audience to theatres, but it’s a television audience looking for television stars.

Casualty 1907(Sunday, BBC1) - well, I thought, is it really going to be any better being on at seven minutes past seven? This is set to be a big series, to be sold all over the world, no doubt as an advertisement for what London is really like. It’s the sort of push-me-pull-you of genres that committees of corporate Tristrams love making: a way of getting all your public-broadcasting eggs in one omelette. It’s popular drama and history, anthropology, education and possibly health information. A medical soap, or carbolic, set in the Edwardian East End, it’s actually better than most classic-novel recreations, though it awkwardly combines nerdy medical fact with stagy melodramatic human interest - which consists of doctors trying to hump nurses. Some things never change.

Oddly, the medicine is far more convincing than the romance. The characterisation of Edwardians is of a species that was apparently socially and emotionally wholly unrelated to humans of even 20 years later, and they are difficult to believe or empathise with. Yet the underlying truth, the real drama of public medicine that relied on charity and the stoical acquiescence of the poor patients, is pretty gripping. And it’s always a pleasure to see the ever-game Cherie Lunghi manfully grappling with the rudiments of drama. After all this time, she never gives up, and one day I’m sure she will be an actress. It’s a lesson to all those amateur kids who imagine that all it takes to be a star is 13 weekends with Lloyd Webber. Out there in the real make-believe world, learning to talk the talk and walk the walk can take a lifetime or longer. And sometimes it’s the audience’s lifetime.

Poppy Shakespeare (Monday, C4) was one of those productions that sucked the life right off the sofa. Physical medicine may have advanced so far and fast that the treatment of disease a mere century ago seems unbelievably barbaric, but not so mental illness. Or rather, mental illness as imagined by most screenwriters and actors. On stage and screen, the bonkers have remained unchanged since Master Will had Ophelia go tonto. The exaggerated, humorous, poignant,Rada-improv games that make up the dramatic psychiatric ward are just as exhaustingly twitchy as they were in Bedlam. Actors love to have a really good, meaty wallow in lunacy. Watching them is one of the most embarrassing, infuriating and insulting things you can do of an evening. The self-indulgence knows few bounds, but lots of drugs. It really wouldn’t be possible to caricature or traduce any other modern illness in the way mental illness is portrayed. The only thing worse than the nutters is the clichéd cartoon villainy of their doctors and nurses.

Madness as a theatrical device is never really about madness, it’s always about sanity. It’s a metaphor, you see, a parable of life outside. The moral is always the same. Who’s really mad? Is it the system or those faint-hearts and subtle eccentrics caught up in it? This particular outing into other people’s unhappiness had even less justification or point than they usually do. What the cast were actually suffering from, apart from award-winning overacting and loving themselves, was unclear. What the story was about and what we were supposed to glean from it was shrouded in the repetitive, glib, agitprop writing. Madness may well be a great human simile, as it was in One Flew over the Cuckoo’s Nest, or a masterful dramatic coup, as it is in Lear. Yet that’s not what it feels like to be mentally unwell or to treat those who are. Television should be more respectful when dabbling in the misery of others for such small effect.

Bionic Woman(Tuesday, ITV2) turned out to be another medical disaster. Running very, very fast using speeded-up film is only ever very, very funny, never ever exciting or believable. It makes the poor woman look like the end of a Benny Hill sketch. All it needs is a little bald bloke.

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