The newspaper and ex-porn baron has built a reputation for a flamboyant style. Now it's the turn of Channel 5 to tremble when he gets his duck horn out

Every decade gets the media villain it deserves. Rupert Murdoch's emergence at the Sun in the 70s coincided with the coarsening of British life and he gleefully exaggerated it; nobody better exemplified 80s greed than Robert Maxwell, preaching probity while raiding his employees' life savings to keep himself in helicopters; Conrad Black, meanwhile, personified exactly the cult of the CEO and the corporate hubris of the 90s. In this tradition, Richard Desmond, for 10 years now the proprietor of the Daily Express has been the man for our times.

In the photographs that accompanied his £103m purchase of Channel 5 , Desmond was pictured outside the station's Covent Garden offices under a banner that advertised one of the channel's shows. "Don't Stop Believing," the banner read. It might have been a caption to Desmond's recent career. If there has been one commodity that Desmond has traded in over the last decade it is the credulity of the British public. He has made it his mission to explore the outer reaches of the idea that you couldn't make it up. For the most part, it has been a tremendous success.

Most rich men who buy into papers do so in order to purchase political influence; Desmond is a curious exception. He seems to buy papers – and now television stations – principally in order to offer final scientific proof of the adage that: "No one ever went broke underestimating the intelligence of the public."

When he purchased the Express group in the millennium year, with the fortune he had made from porn magazines at Northern and Shell, he placed most of his editorial faith in the idea that, contrary to all natural law, the obsession with celebrity, which he had nurtured in the pages of OK!, still had plenty of life left in it.

Rosie Boycott, the hapless editor he inherited, recalled him toasting his arrival in the company of the Beckhams – whose wedding he had lately "bought" for a million pounds – in his penthouse office: "Fuckin' hell, I own the Express. And David, you're the best footballer in England. Fucking brilliant. Victoria, you're the most famous pop star in England. Fucking brilliant."

Even Piers Morgan, at that time editor of the Daily Mirror, was beginning to have sweaty existential fears that there might be more to life than soap stars showing their knickers getting out of taxis, but Desmond was nothing if not dogged in his beliefs. Thus, while other media barons have been fretting of late about "digital platforms" and "e-readers", Desmond has been evangelical and steadfast in his concentration on content. "TITS! TITS! TITS! On a big blonde bird. That's what I want on the front of my magazines," was how he reportedly defined his philosophy at a staff meeting shortly after purchasing the Express.

It says much for this faith that the slight decline in the circulation of OK! this year was attributed not to changing multimedia habits or the complex fallout of the credit crunch but to the fact that, according to one business analyst in the Times: "Katie Price may have got married to Alex Reid this February but that's not as good as divorcing Peter Andre last year."

For someone who once presided over a range of titles that attempted to create a taxonomy for the infinite range of human desire – Big Ones, Fifty Plus, Readers' Wives, Big and Black, Horny Housewives, Only 18, Mothers-in-Law – Desmond has a contrarian's taste for simplicity. His business "genius" is widely attributed to two things: an unrivalled relish for cost-cutting – half of his newspaper group's staff were dispatched on his arrival; the seven executives lost at Channel 5 are no doubt only the beginning of his television cull – and an instinct for "cross-fertilising" content across the various strands of his empire, a philosophy that suggests that however thinly entertainment is spread, it might still be spread thinner.

Over the course of Desmond's ownership, no one could accuse any of his titles of a lack of trust in this formula. The Express group stretched the truism that "Princess Diana sells newspapers" for many, many years after every other media outlet had given up on her ghost; its coverage of the disappearance of Madeleine McCann took obsessive compulsive publishing to new extremes; the newspapers' defeat in the libel courts, and payment of £550,000 to the McCanns, detailed "well over 100" front pages of the Daily Express alone that included entirely fictitious allegations.

"It's not work, this," Desmond likes to say, "it's fun." The story goes that he learned his boardroom skills by accompanying his father, the managing director of Pearl and Dean, the cinema advertisers, to meetings. Clive Desmond had become deaf through illness and his six-year-old son apparently did his listening for him. More formative perhaps was the fact that when his parents divorced – after his father gambled the family savings away – when he was 11, he moved with his mother and lived in a flat above a garage in Finchley, north London.

According to Desmond, he was "very fat, very young and very lonely" at grammar school, and when "the mothers and fathers would pick up the other kids in the car, he'd be getting on the bus"; he left school at 15. The initial ambition was to take out some of his frustrations on a drum kit – he formed a blues band and still plays charity gigs with the likes of Robert Plant and Roger Daltrey – but he subsequently seemed to discover that it was more cathartic to knock the heads of subordinates together.

Unpredictability is the key to his management style. Desmond tends to deny, with a grin, the more lurid stories – the executive he locked in a cupboard, the marketing man late for a meeting who was ordered to stand on a table and drop his trousers and describe himself as a cunt – though he has suggested that his employees enjoy the "colour" these tales add to the daily grind. His longer-term staff attest to an unswerving loyalty from their boss and to his abiding sense of "mischief", his employment of a duck horn, for example as a response to ideas he doesn't like.

His real venom, they say, is reserved for the opposition. Desmond's bête noire, Lord Rothermere, the Daily Mail chairman who inherited the job from his father, he delights in calling "Little Johnny" and a "lucky sperm". Desmond has the self-made man's loathing of dynastic wealth, though of course, when the time comes, he plans to hand over his empire to his own fortunate gamete, currently at Cambridge.

For a while, Desmond seemed to be at pains to try to recreate himself as an establishment figure, troubled by questions such as: "Is it worse to be described as a pornographer or a former pornographer?" These days, he appears happy just to be talked about, even by Private Eye, as "Dirty Des", and making money. He has a paternal pleasure in the expansion of his empire across the world, the bravura British export of Kerry Katona and "upskirts" to "India, Australia and China". He has taken PR advice from his friend Philip Green, the government's billionaire austerity consultant, "that you shouldn't hold grudges. I used to get all hung up on that bloke said this and another bloke said that..." As if to prove the point, Stephen Pollard, whose final leader for the Express spelt out the words "Fuck off, Desmond" using the first letter of each sentence, was offered his column back on the paper.

Desmond, when he talks about himself, takes pride in his honesty: "Unlike them," he says of most of the rest of the world, "I am not a hypocrite." He is a family man, an observing Jew, who cycles around newsagents in north London on days off checking they have his headlines – "Now asylum if you're gay", "Brit kids forced to eat halal meat" – appropriately displayed. He is a generous patron of various charities, including Moorfields Eye Hospital and Tower Hamlets Women's Aid. His lucrative subscription porn channels, Red-Hot TV and Television-X, are "proper adult entertainment"; he deals in "real" celebrities such as Jordan, not "toffs on polo ponies".

When he discussed the philosophy of the Express with his staff they came to the conclusion that what they believed in was: "Justice for the guys with a bit of get up and go who want to make something for themselves and their families and look themselves in the mirror and say, 'Good, that.'" Pretty straight guys, like the "socialist" billionaire who would have them believe they buy "the greatest newspaper in the world".

THE DESMOND FILE

Born In north London on 8 December, 1951. His parents divorced after his father, the managing director of cinema advertising company Pearl & Dean lost the family money by gambling. Desmond left school at 15 and joined the Thomson group, selling advertising for trade publications while playing the drums at night.

Best of times In a word, now. The acquisition of Channel 5 is a new high point for his self-made media empire

Worst of times Following his parents divorce aged 11, Desmond moved with his mother into a flat above a garage and has described his impoverished early adolescence as a time when he was "very fat and very lonely". .

They say "He does not walk around ordering things. He does walk around the newsroom from time to time, as it happens, but he does not get involved." Sunday Express editor Martin Townsend

"He is a proprietor without propriety." - Don Foster, MP, former Liberal Democrat culture spokesman

He says "Running newspapers is the most fantastic fun you can have... it's just the same as a band. Your editor is your lead guitarist, your bass player is your number two, you've got the circulation manager at the keyboard, and you're sitting there drumming, trying to add passion and sparkle and keeping time."