LOS ANGELES -- Producer Don Hewitt, creator of U.S. television's most successful long-running show, 60 Minutes on CBS, really is elderly. He uses antiquated expressions such as "Atta boy!" and always wears a sports jacket and tie, but still doesn't look old enough to draw social security. Yet on Saturday he marked his 80th birthday and went on to produce the Sunday show as usual.

Its investigative-news format has been imitated worldwide, and the ticking stopwatch is one of the small screen's most recognized logos. Ratings have declined from its leadership days, but 60 Minutes ranked No. 6 earlier this year and will end the season in the top 20.

Hewitt now joins two other octogenarians on the show: interviewer Mike Wallace, 84, who joined at its inception in 1968, and commentator Andy Rooney, 84 in January. Interviewer Morley Safer, born and raised in Canada, is 72, and the female star, Lesley Stahl, turns 61 tomorrow, making her one of television's oldest reporters in a medium notoriously unkind to older women. (Show colleagues Ed Bradley, 61, and Steve Kroft, 57, are the other youngsters.)

Despite his unquestionable success, CBS is considered replacing Hewitt with someone younger, but he promises to "die at my desk." If the network does have the temerity to dismiss him, he threatens to go elsewhere and says he already has two offers. "You can't run a network based not on how good you are but how old you are," he declares. A fine sentiment, but unfortunately not true.

Television, and the movies, are obsessed with youth and the shelf life of its performers and writers dwindles continually. It used to be the dreaded "4-0" for actors (with obvious exceptions), especially females, but in some cases old age in Tinseltown sets in during the 20s, even for writers, whom the audience never sees. Hollywood once had a notorious blacklist of political radicals; today it has a greylist of "oldies."

The most ludicrous example was Kimberlee Kramer, an actress-writer who legally changed her name to Riley Weston and wowed the producers of WB's coming-of-age "relationship" series Felicity, about a college girl, by writing sparkling scripts as an 18-year-old prodigy. Entertainment Weekly included her in the top 100 talents of 1998.

But despite gossipy stories about her babysitting experiences, the 19th-birthday party the Felicity folk held for her, and her habit of bringing her mother to meetings, a show-business trade paper revealed her shocking story in October that year. Weston-Kramer was 32, and divorced. Her agency dumped her, and a proposed $500,000 two-year deal with a Disney subsidiary faded.

Too old at 32? Absolutely. A producer of the ABC sitcom Spin City is on the record as saying that writers over 29 were deliberately not hired. Some writers complain they cannot find an agent once they pass 50, making it almost impossible to present scripts.

The Spin City example comes from a motherlode of ageist evidence amassed by a law firm in Washington, which is pursuing a huge damages case against the major film studios, TV networks and Hollywood talent agencies for discriminating against older writers. In the suit, backed by the American Association of Retired Persons (AARP) and filed in Los Angeles, 150 to 180 writers in each of 23 class actions seek $200-million (U.S.) compensation.

The lawyer handling the case, Daniel Wolf, said: "Our opponents are trying to obstruct the case but will not argue the merits, because if they do it's clear they are being discriminatory. With actors, a 50-year-old cannot play someone of 20, but are they saying that a person of 50 cannot write about someone aged 20? The bias becomes even more obvious if you substitute race for age and see how they are arguing, in effect, that a black person cannot write about white people or vice versa. If that was really the case, there would be uproar."

While writers go to court, actors are more cautious. It is Hollywood, after all, that condemns its opponents with the remark: "You'll never work in this town again." People say it, and it happens, but even during the blacklist writers could use proxies. Actors cannot.

Lacking a legal case, the Screen Actors Guild has produced some damning research. In a survey last July it found that performers under 40 were "highly favoured" and "nearly twice as many roles in television and movies were cast for actors under 40 than those over 40, although Americans aged 40 and more comprise 42 per cent of the population." Women do worse. Those aged 40 and over had only 24 per cent of the roles, but the under-40s got 71 per cent altogether and 78 per cent of female leads in feature films.

The anecdotal evidence is everywhere. Among the fading stars of yesteryear are: Demi Moore, 40, Daryl Hannah, 42, Jamie Lee Curtis, 44, Sharon Stone, 45, Geena Davis, 45, and Melanie Griffith, 45.

Actual anecdotes have become Hollywood folklore. There was the time the late director Stanley Kramer (High Noon and three Oscar nominations) sat opposite a 30-ish studio executive who invited him to "tell me about yourself." Kramer stared at him and then said: "You go first." Or when Shelley Winters had a similar experience and told the young mogul: "I'll be back soon." She returned to his office later that day and without saying a word, plonked her two Oscars on his desk.

Tinseltown is youth-obsessed because industry executives insist that older people do not visit cinemas. It is true that teenagers may be the only demographic group in the world who pay to see the same movie five times, but if the over-40s do stay away, might it not be because they are offered so little? They are not seduced by noisy explosions and no longer laugh at fart jokes.

Yet Hollywood cannot even get this straight. Against protests, it continues to screen May-December romances in acute disproportion to reality. Some recent examples: Anne Heche, then 29, paired with Harrison Ford, 56, in Six Days, Seven Nights; Warren Beatty, 61, and Halle Berry, 29, in Bulworth; Kristin Scott Thomas, 37, and Robert Redford, 61, in The Horse Whisperer; Helen Hunt, 34, and Jack Nicholson, 61, in As Good as It Gets; and Gwyneth Paltrow, 25, and Michael Douglas, 55, in A Perfect Murder. Paltrow said later: "It was weird kissing him because he was an old friend of my father's and I used to call him uncle."

Ageism in television is more subtle but perhaps more invidious. Don Hewitt blames "a bunch of kids in advertising agencies." These folk, predominantly in their 30s, have established a dubious tradition: that selling to older people is a waste of time because they made up their minds long ago about their purchasing preferences. Only the young, the argument goes, are available to develop brand loyalty. To them, Budweiser is such an alluring novelty that once they sample its delights, they are hooked forever.

The result of this thinking is that although 60 Minutes has a bigger audience than many rival shows, its viewer profile is older, so the network is paid less for them. Yet persuasive evidence has demonstrated for a long time that the brand-loyalty theory no longer works.

Not only do people aged between 35 and 64 account for nearly two-thirds of consumer spending, they are among the least loyal to brands. A 1996 market-research study found that women in that age group were more likely to switch brands than their younger sisters. The next year the television audience company, A.C. Nielsen, discovered that baby boomers (those born between 1945 and 1964) tried as many different makes of soft drinks, beer and chocolates as those in their 20s.

So who are the real conservative, inflexible dullards who cannot be persuaded to change their minds? Why, the young folk of Madison Avenue, constantly peddling their ageist nostrums to gullible networks.

Doris Roberts, 72, one of the few American actresses of her age still to prosper on U.S. television, as the cantankerous mother-in-law in the hit comedy Everybody Loves Raymond, won her third Emmy last year for the role. She told the Senate Special Committee on Aging in Washington: "My contemporaries and I are denigrated as old coots, old fogies, old codgers, geezers, hags and old timers. We are the only culture that so denigrates old people. It's wrong and the image makers of America should be ashamed."

Although other countries have their ageist attitudes too, none has the power of Hollywood to do something about it. Yet Roberts's appeal is unlikely to help. Wolf's lawsuit stands a better chance.