Though cameras are rarely present, notebooks and recorders often frowned upon and audiences are bespoke, after-dinner speaking offers media personalities one of their most lucrative platforms. Almost all of the A-list of such oratory is made up of media figures; Sir David Attenborough, Angus Deayton, Alastair Campbell, Piers Morgan, Richard Hammond, to name a few. Almost all of them are men.

One man more than any other in Britain is responsible for this flourishing industry. With his open-neck pink shirt and rotund features, there is very little of Lear in Jeremy Lee, the charming brain behind Jeremy Lee Associates, the largest speaker agency in the country.

A graduate of York University, where he studied English, Lee's early acting ambitions were soon inhibited by forces beyond his control. "I was just too short to be an actor," he says. "I soon realised that my height [he's 5ft 7in] would be too big an obstacle. Plus I can't really dance".

So he got a job booking "talent" – the generic word Lee repeatedly uses – for the agency MECCA. In 1990 he decided to blaze his own path, setting up JLA and acquiring an ever-growing army of speech makers. This year, JLA's 18th, "was the year we finally came of age".

JLA now boasts of booking over 1,600 engagements each year, with an army of speakers numbering several hundred. Increasingly, Lee says, those doing the booking aren't just corporate entities; the public sector too is coming to value a good speech more than ever.

"Crudely put, there are two reasons why people want to see a speaker, and obviously they're closely related. The first is that it can put bums on seats, which most people who send out invites are keen to do. The second is – and I'm afraid it's a very objectionable phrase – the so-called "wow factor". There are some speakers out there whose very presence is motivational, and who lift people just by virtue of their presence".

On his website, Lee has graded his speakers from E to AA, with a price to match. To achieve AA status you basically need to have walked on the moon, like Neil Armstrong and Buzz Aldrin. Most after-dinner speakers will back themselves to make a good speech, which can be a source of satisfaction in itself. And with pay packets ranging from £1,000 for an hour (Band E) to £25,000 plus per hour (Band AA), the financial rewards are huge.

But there's more to it than that. In recent years, politicians in particular have been heavily admonished for accepting huge sums for their after-dinner speeches. The publicity has not been all good. And in times of belt-tightening across the country, readers may find the discovery that a familiar face was paid thousands for not much work galling.

Why, then, should a media personality wish to court such danger? Largely, Lee explains, because of money. But it's also partly because, so long as they manage it safely, the publicity needn't be all bad, and the audiences are usually decent company. The public may tend to be intolerant of politicians lining their pockets; but an established journalist or television presenter doing so is usually seen as fair cop.

"High-profile individuals attract attention when they start speaking on the circuit", Lee says. "But almost by definition, they are speaking behind closed doors. Apart from that burst of publicity, which is often written up as a "shocker" – so-and-so got paid x amount for speaking to blah, blah, blah – the circuit doesn't actually get that much profile unless the speaker is already hugely in the public eye."

Lee says that the motivation is rarely the kudos of speaking or the opportunity to network with an audience. "Yes, of course you'll make contacts, just as you would if you went for dinner with friends of friends, but that's not always explicitly what speakers are after. It's often the slightly coarser fact of getting paid well".

There are those in the media who decide that, because of the negative headlines generated by speech making, and the dangers of guilt by association with the wrong crowd, they want nothing to do with the "circuit". Lionel Barber, the Editor of the Financial Times whom Lee describes as "a deeply impressive individual", refuses on principle to do after-dinner speaking.

Lee claims that the system of banding speakers according to their price tag is his own invention. But though he has a role in influencing which band a speaker enters, he says he remains subservient to the market.

"I explicitly reject the idea that I am some sort of arbiter of social worth. Quite the contrary, in fact: this marketplace works according to the laws of supply and demand, just like any other. Where I do come in, if at all, is in recommending that speakers who are new to the circuit enter at a lower band than they think they'll end up, because moving upwards is a lot more commercially sensible than moving downwards, which looks awful".

Nevertheless, distortions exist. Award ceremony hosts from Bruce Forsyth to Stephen Fry can command huge sums, depending on the size of the ceremony. And somebody like Peter Fincham, the Director of ITV who was chosen to give this year's MacTaggart Lecture at the Edinburgh International Television Festival, ranks only as a "C" according to JLA.

Though methods vary, the secret of a good speech can often be boiled down to a simple dictum. "Try to tell your audience something they don't know about someone or something they do know," Lee says. "Know your audience, and make sure to get your pitch right from the beginning."

More famous speakers get an easier ride. "Someone like the comedian Dominic Holland, who is excellent, might have an awkward opening minute where he's got to immediately win over a crowd that may be unfamiliar with him. Someone like Gorbachev [the former Soviet President] usually gets a bit longer".

Over the past few months, Lee has been obsessively working on a new website for JLA, which will have expanded biographies and forums on which audience members leave moderated comments about speakers they have recently seen. Bookings for next year are up between three and five per cent so far, despite widespread economic gloom. "Ultimately, though much of the coverage of the circuit focuses on the money involved, it's getting more and more popular with both audiences and speakers," Lee says. "I think that's because, at some level, everyone can enjoy a good speech well delivered. Most of our speakers leave their audiences feeling either better about themselves or enlightened. That's a fantastic thing to be involved in, frankly".