Because it's not actually that easy to get on the box. Jon Roseman, an agent with 25 years' experience, gets 1,000 letters and videos every year from aspiring young presenters; most go straight back by return of post. So he has decided to tell wannabes how to go about it properly. Today his first eight eager novices are turning up to his west London office for a three-hour seminar that will cost them each pounds 205.63 (that's pounds 175 plus VAT).
Roseman, hugely energetic, strides around enthusiastically, smoking Dunhill cigarettes. He represents a stable of household names, among them Tania Bryer, Jill Dando and Roger Cook. He is scathing about current standards. "It's true that most of the techniques for appearing on telly are learned on the job - though the quality of the producers and directors today is not very high and even the professionals don't get much advice. But some of them, you'd think they'd had a lobotomy."
Is he hoping a new Paxman might shine out among his pupils? "It's difficult to tell. People can be witty and charming, and then clam up totally in front of the camera. If they've got determination, and the ability to accept total and utter rejection time and time again, then maybe, who knows?"
The eight hopefuls file in: six men and two women, all but one in their early-to-mid twenties. ("Television is very ageist," warns Roseman. "The chances of anyone post-35 getting a job in television are minimal.") Once everyone has found a seat, Roseman launches in without preamble.
"Anybody can be a presenter. You see them on television every day and can't believe it; you think that some of these people shouldn't be allowed to own a television, let alone be on one. Crap people are getting oodles of work. It's down to 60 per cent luck, 20 per cent intelligence, and 20 per cent manipulation."
Everyone nods and smiles. This is encouraging. But sadly, even though anyone can be a presenter, it doesn't mean everyone will be one. In fact, most people won't be. "I can't tell you why some people get work and some people don't," says Roseman candidly. "It can depend on anything. Sometimes it's just down to what time of day the producer sees your showreel. Sometimes they'll hate you at 10.30 in the morning, and love you at four in the afternoon. Or your tape might come in sequence after someone who's really good."
Discussing showreels takes up a good proportion of the morning. A showreel is a three-minute video which showcases the talent of the person looking for work. "You won't get to see anyone," says Roseman, "so your showreel has to be right. If they don't like you in the first 30 seconds, they aren't going to spool on until they find a bit where they do like you."
There's no point in getting your best mate to sling together a few fuzzy camcorder shots one Sunday afternoon of you at the desk in your bedroom, saying "Here is the news" and "Now, let's look at the weather" in your best Trevor McDonald/Kate Adie voice. You need, for example, to demonstrate such essential skills as walking and talking at the same time (less easy than it may appear - think of all those hilarious out-takes of presenters smacking into trees and bollards, disappearing down holes in the road, etc).
Before you even think about getting in front of a camera, preparation is needed. Much depends on what you aspire to. If it's the News at Ten, a degree and some journalistic experience are de rigueur. But some basic truths hold true, whether it's Newsnight or The Big Breakfast you're aiming at.
"Go to a voice coach," says Roseman. "It's essential. They will also do some basic body language, how to walk, talk, breathe. You'll need four or five lessons at pounds 25 to pounds 30 a time. Get a good cameraman for your tape - there are plenty of ads in Broadcast magazine. Then take it to a post- production house and have it properly edited." Don't wear a hat and avoid glasses unless you are ridiculously baby-faced.
One brave soul, a European weather girl keen to move on to fresh challenges, has gamely brought her own showreel along. "Cut your hair," advises Roseman, looking at her beautiful long mane. "Ninety-five per cent of women in television have shortish hair. Long hair blows all over on location, and in the studio it's a pain. Ditch the weather clips on your tape. Get out and do some vox pop interviews."
The weather is a sticky trap, it seems. "It's very difficult to move on from weather and children," says Roseman. "If you can choose not to do weather, don't do it. And children's television - it's a great run for three or four years, then you're 23 and too old."
Realistic goals are good, though, even if they do consist of pointing out warm fronts over the Welsh borders, or constructing Barbie homes out of cardboard cartons. "When you ask people where they see themselves in five years' time, and they say 'Fronting my own show' you think 'Ohhhhh Goddddd'," says Roseman, with an indescribable grimace.
Useful nuggets of information pour out as everyone scribbles madly. Tape your voice, listen to it over and over (regional accents are good, there is a movement away from cut-glass middle-class). Have some good photos taken (and, girls, don't waste time and money on sexy shots; head and shoulders with nice smile works better). Roseman brings in the psychologist Dr Aric Sigmund (co-incidentally, a client) to talk about presenter psychology.
"Should we hang out in the Groucho and the Coach and Horses?" asks one hopeful. Nope, waste of time. The last thing a producer having a quiet drink will want to be confronted with is you, with a wide smile and a showreel in your hand.
The session runs over the advertised three hours. It has certainly been intense. It has also been fun; no-nonsense advice is larded with showbiz gossip and stories of the stars. (These also have a practical application. When Roseman's pupils are all so famous that no one can tell them what to do, they will all know never to attempt a chat show, like one big name who crashed in flames last week, and always to insist on non-transmitted pilots for any new show, like another who is very rich indeed.)
So has it been worth it? "I've seen courses like this advertised for pounds 800. I think I've saved money by coming," says Joanne, 23, who has travelled all the way from Stockport.
"You have to cut the crap and go to the chase like this," says David Bouchet, 28, a sound engineer. "Lots of people will take your money and make promises that are mostly bullshit."
Roseman laughs genially. "I think my advice is worth at least pounds 30,000."
If it gets any of them on the road to fronting Newsnight, they might well agree.