Lorraine supreme - Lorraine Kelly

OVER a two-decade television career, Lorraine Kelly's breasts have become as famous as she is. The Hollywood actor Robert Downey Jr memorably complimented Kelly's embonpoint during a daytime TV interview in 2005. "You look fantastic, you look really well," Kelly offered by way of welcome, warm but also alluding to the fact that the actor had successfully emerged from a well-documented low period, when his drug addiction resulted in a spell in prison.

"Thanks," he smoothly responded. "I was going to say that your tits look great too!" A blushing Kelly recovered from this cheeky rejoinder, but it made headlines, elevating the mumsy presenter from East Kilbride to sex-symbol status.

A few months ago she drew attention to her womanly assets again when photographed at the launch of the Scottish National Portrait Gallery's current Vanity Fair exhibition. Posing in front of a sexy Jean Harlow portrait from the 1930s, she upstaged that blonde bombshell in a black chiffon gown that plunged dramatically and framed the now celebrated (but normally covered) bust.

Kelly's breasts also have a serious role to play: once a year she pops them into a lavishly decorated pink bra to publicise the Moonwalk, raising money for breast cancer charities. A patron of the Association for International Cancer Research, she's done two Moonwalks in Edinburgh to boost funds for research, care and prevention and has also run the London and New York marathons.

Now the undisputed queen of early morning TV, rumoured to earn in the region of 500,000 a year for presenting LK Today four times weekly, Kelly this week publishes her autobiography. It's bound to sell in barrowloads to the millions who tune in to watch her every day, but although the boob stories are, er, titillating, frankly it's a stretch to imagine what someone who's renowned for being nice and well-grounded might say that's going to keep us all glued to its 320 pages.

The memoir, Between You and Me, will undoubtedly contain frank accounts of Kelly's working-class origins and entry into local newspapers as a teenager, but bitching about life inside the high-octane TV industry simply isn't her style. Straight-talking, no-nonsense niceness and an evident lack of egocentricity are the qualities upon which her career has been built. Is remaining utterly normal really all it has taken to make her Britain's equivalent of Oprah Winfrey: a one-woman force for good who, on LK Today, makes viewers laugh, cry and empathise with a mix of features covering anti-cellulite tights, family tragedies, celebrity gossip and fashion tips, all in a half-hour timeslot?

Her background may be the key to her reputation for pragmatism and sincerity, which she has nurtured along with a warm, engaging presentational style. Giggly and spontaneous she may be, but there is a surefooted professionalism underneath.

Kelly, raised in Glasgow and East Kilbride, has been the most constant female presence on Britain's breakfast-time sofas for almost 20 years, since she first appeared as a presenter on TV:AM in 1989 and went on to co-launch GMTV in 1993.

She entered as a qualified journalist, trained on the shop-floor, and worked her way up. She's cute, but no autocutie.

She started as a teenage cub reporter on the East Kilbride News, then became a researcher at BBC Scotland in 1983. She left when told her accent would prevent her from getting work as a TV presenter – and offered elocution lessons.

Indignant, Kelly neither wept nor moped, neither did she adopt a bizarre accent for the screen (pay attention, fellow GMTV-er Carla Romano): what she did was telephone Greg Dyke directly at ITV to ask for a job. She was snapped up for TV:AM and a legend was born.

Kelly's star has risen steadily ever since: there has been no blip in her popularity, no tall-poppy syndrome, no skeletons tumbling out of cupboards. Even in the ruthless world of TV, it seems no one's got a bad word to say about the woman. The programme editor who accidentally sent an insulting text about Kelly directly to her mobile phone immediately apologised and resigned, rather than try to convince anyone that the presenter actually was the "nightmare" she had accused her of being.

Past interviewers have all said Kelly is the same off-screen as on: she herself claims to have an in-built "bullshit detector". Nor is there any showbusiness-like detachment – she laughs off any wardrobe malfunctions, weight gains and bad-hair days.

Straight men lust after her (look up The Lorraine Kelly Appreciation Society online), students idolise her (when she became the first woman rector of Dundee University in 2004, she went on a pub crawl with its women's rugby team), women want to emulate her (there's a page on the GMTV website where you can check out what Lorraine's been wearing) and gay men want to befriend her (she scored points when, in an interview for gay men's magazine Boyz, she confessed she'd once had al fresco sex, albeit with her husband, Steve Smith, a cameraman whom she married in 1985). The fact that chat show hosts Jonathan Ross and Graham Norton have wooed her, and that she has appeared on panel programmes Never Mind The Buzzcocks and Question Time testify to Lorraine Kelly's status as an everywoman for our age.

She's forever being asked when she'll "move on", but why would she? No-one asks that of US daytime queen Oprah.

Yet breakfast TV is far from being all she does: Kelly has written books on parenting, health and diet, full of homespun wisdom and dollops of common sense. She writes a newspaper column and is a magazine agony aunt; she has even brought out an exercise DVD and still we like her.

Having been at the top of her game for nearly two decades, Lorraine doesn't boast about it. She lives between London and Blairgowrie in Perthshire and has a 14-year-old daughter, Rosie. She likes a laugh and tells it like it is. In a world of airbrushed, mealy-mouthed media clones she's a blast of robust Scottish air.

Two American economics professors recently calculated that Oprah Winfrey's endorsement of Barack Obama was worth a million votes to the presidential hopeful. I don't suppose there are many UK politicians with the vision to see it, but just imagine what Lorraine could do … Gordon Brown could do a lot worse than try to get her on side.