IT'S CLARE BY A HEAD FROM WILLIE

AS YOU APPROACH up a metal staircase, sound-proofed with rubber inlays, you hear the noise from the television presentation box at Newbury racecourse. Pitched somewhere between the whinny of a horse in the act of foaling and the maniacal laughter of Jack Nicholson in The Shining, this high-pitched cackle is instantly recognisable to all who follow horse racing.

It belongs to the 55-year-old Scottish ex-jockey Willie Carson. When he retired from riding two years ago after serious injury, some may have thought, perhaps even hoped, that it was silenced for good. But no: "Here's Willie!" again. And now he's standing on a chrome camera-box so that he can level up to his tall, heftily built co-presenter of BBC racing, Clare Balding.

Outside it is a gloriously warm, bright September afternoon. But the weather only adds to the heat in the stifling glass-panelled box overlooking the parade ring and winner's enclosure, where the lighting rig is blasting hot air at the pair. Willie's in a grey suit with one of his flash racing ties, Clare looks dressed for October in a plain olive green number with a touch of Cell Block H.

But as they wait for their cue from the floor manager, they seem neither hot nor bothered, nudging each other playfully and bantering about horses, with the Carson cackle as regular punctuation. And then suddenly they're on air again, live, and though their focus now is on the camera, they don't change their manner. There's no stiffening, no pulling down a mask of pomposity, no nervousness. They are as much at ease on camera as off, which may be one of the reasons for the success the pairing has enjoyed since they were pitched together as presenters in January this year.

"Another win there for trainer David Loder," Clare says, taking the producer's cue in her ear-piece, "whose record with two-year-olds this season is quite astonishing. He must wind them up the way you wind people up, Willie." And Willie giggles in response, as though he has been caught loading his catapult by a schoolteacher.

Clare's record with 55-year-old is clearly pretty good too, and soon the two of them are expertly shooting the breeze for the benefit of the afternoon audience of 3 million or so. Clare's precise diction and grammar blend pleasingly with Carson's more tangled syntax, and whenever Willie gets lost in the maze of his own words, Clare steps in to lead him out of trouble.

"She belittles me," Willie says with a grin to the camera. In these few moments, you begin to appreciate why the relationship has worked. Far from playing Clare as the "naive young niece" to Willie's "wise uncle", the producers have cast her as the authority figure, with Willie as the irreverent jester who runs the risk of being back-handed off his box by Clare if he steps out of line.

It is a reversal of the usual television format of the frivolous, giggly girlie and the serious, coiffured male host. And there's no sofa either - Clare and Willie are on their feet throughout the two hours of the live broadcast that embraces four races. Audiences are lapping the format up, as are the critics who have been praising the revival of the BBC's racing coverage and citing Willie and Clare as the major factor in this success.

Carson comes from a working-class, non-racing family in Stirling, and survived a tough apprenticeship before gradually climbing to the top as a jockey. He has four Derby wins among his haul of Classics, and would probably still be riding but for a horrific accident two years ago. Balding, on the other hand, is a country-bred 27-year-old Cambridge graduate whose father, Ian, trains horses for high-profile owners which include the Queen.

At one time, Carson's wife, Elaine, was a nanny to young Clare - shades of Upstairs, Downstairs. Now Clare is a de facto nanny to Carson on air, brusquely shutting him up when he looks as though he's straying into dangerous territory, and they have become perhaps the most intriguing double-act in sport since Harry Carpenter swapped jive talk with Muhammad Ali.

The horse-racing community in Britain is relatively small, yet it took a set of fairly bizarre circumstances to bring Willie and Clare together on the screen. It involved, in chronological order, a violent horse, a surprise retirement and the hunch of a New Zealand-born sports producer with a background in light entertainment.

The sequence began in September two years ago when Carson, who was still good enough at 53 to be getting top rides, was preparing to mount a horse called Meshhed in the parade ring at Newbury. The horse lashed out with both its hind legs, catching Carson in the stomach, knocking him six feet into the air, and sending him crashing into the surrounding fence. He was rushed to hospital where examination revealed that his internal injuries included a dangerously bruised liver. The severity of the injury required a month in hospital and most observers felt that Carson would take this as the cue to retire.

At the time, Clare Balding was in her third year as a junior sports presenter on the BBC's Radio 5 Live. Though her natural arena was horse racing - in addition to the family connection, she has ridden competitively in ladies' races on the Flat - Balding had studiously avoided specialisation, preferring to establish herself as a good all-rounder. Over a cup of tea and a quick Marlboro Light in one of Newbury's smart bars, she says: "When I came into the BBC five years ago, I really didn't expect that I'd be involved in racing to the extent that I am."

This may seem a touch naive, given her background, but it is likely that Balding was always sensitive to suspicions of nepotism. However, her elevation to television presenting had been set in motion by another event that September, when Italian jockey Frankie Dettori rode all seven winners on the card on the Saturday of Ascot's Festival of Racing. This seismic achievement required extended coverage from Grandstand as the nation tuned in to watch. It also lifted racing's profile on to the front pages of all the newspapers for several weeks afterwards.

"I was still lying in hospital at the time," recalls Willie Carson, who's joined us for tea. "When I watched the races, I knew in an instant that what Frankie had achieved would carry racing over to a much wider public. It wasn't just the seven winners, but Frankie's bubbly personality too. Mind you, if I'd been riding that day, he wouldn't have had seven winners!"

Carson's trademark cackle inevitably follows. It is an interesting device, deployed strategi- cally in order to take the edge off the cutting remarks that he is inclined to make off the cuff. It is similar in effect to Roger Moore's interview technique, where the truth is passed off as a light-hearted throw-away, as in: "It was a terrible script but they offered me so much money I couldn't turn it down." There's no doubt, too, that some people find Carson's tinkling giggle disarming, suggesting in someone of his stature the impish schoolboy.

This wasn't always the case. He was a stroppy git to racing reporters through most of his career. I recall travelling to Newmarket for a pre- arranged interview between races. After I'd been introduced by his agent, Carson started muttering repeatedly, "I don't know about you, I'm not sure." Eventually I was told to call him at home that night, only to get more of the "I'm not sures." Finally he agreed to talk, but warned, "If you stitch me up I'll get to hear about it," as if something in a national Sunday newspaper could be hidden from him.

But the Carson sitting opposite me today at Newbury is free of paranoia and happy to talk about his new media career. "I'm just a beginner," he insists, air-brushing out several seasons as a captain on the sweaters- and-sideburns television quiz A Question of Sport. Despite his multi-millionaire status - Carson usually flies to racecourses in his light aircraft - he is quick to sense the sudden emptiness that can ambush those that take late retirement from a sport. "I'm a naturally busy person, and I knew I'd be looking for something better than just sitting at home," he says.

As soon as Carson announced that he would not ride again, the BBC's racing correspondent Julian Wilson, an old friend, put his name forward as a candidate for the team. The racing producer, Malcolm Kemp, who was looking for ways to attract and retain the new audience that Dettori Day had generated, readily accepted the idea.

Perhaps because of his entertainment background, Kemp felt that the BBC's coverage "had become slightly stuffy, even a little elitist", and had decided to do something about it. Carson was the first new element, and at Royal Ascot in 1997, Balding was brought in to add a younger voice.

The line-up wasn't entirely convincing: Julian Wilson, the BBC's racing presenter for over 21 years, looked distinctly uneasy flanked by Carson and Balding on the screen. The sartorial circumstances - top hats and tails, high-fashion millinery - irresistibly called to mind an arranged marriage, and one you felt would not work out. "Three was a crowd at times," Kemp recalls.

Wilson, despite his acknowledged racing expertise, was emphatically of the old school - Harrow to be exact - with a slight tendency to Edwardian nostalgia. At "Glorious Goodwood" that year, he had talked wistfully of "the days when people took a house for the week". Then again, his third Christian name is "Bonhote".

Like a character from Evelyn Waugh, Wilson seemed to be sensing the passing of an age with some discomfort. Perhaps the defining moment of his disengagement came during a session of reading out viewers' faxed questions, when he tried to spring a schoolboy prank on Balding by getting a friend to send in a fax from a "Miss R Soles". What japes!

A month before the long-planned retirement of the BBC's iconic racing commentator, Sir Peter O'Sullevan, last November, Wilson unexpectedly called time too. He made brief mutterings about the new style of racing presentation, but otherwise quit the field with stoic dignity, preferring to save more robust reactions for his just-published autobiography, Some You Win. In this he sourly accuses Kemp of being "determined to pursue the ideology of populism" and "to achieve a heightened female involvement".

Kemp insists, "Clare was the obvious candidate to succeed Julian. I'd been responsible for using her a lot more on television, and I knew she had a bright personality and an accessible manner. There was no question of her getting the job because of who she was, or because a woman was thought to be a necessary gimmick. I simply had no doubt that she could do it and was the best person for the job."

"I thought that I had a chance," Balding says, winding down with relative ease after coming off air, "but I expected them to go for an older, more experienced man." Instead, in January this year, "Clare and Willie" became an item. "I admit that I had to cross my fingers," says Kemp, "but I thought it would work."

Carson, sitting next to Balding, chirps, "When I first heard that I'd be working with her, I thought 'Oh no, not her!'" He then lets rip his cackle - leading one to guess that this was probably true. But Balding doesn't seem to mind. She says she's "used to Willie's wind-ups. We actually get on very well, both on and off the screen."

So it seems, although the absence of that exhausted televisual tease, UST - unresolved sexual tension - probably helps. "I have to call her Ms," Carson volunteers. "And I call you arsehole," Balding ripostes kindly. One presumes she means off screen. In fact, the knockabout banter does not get in the way of their professionalism. "Clare has the ability to be lively and to be seen enjoying herself, yet she retains authority," says a colleague, commentator Jim McGrath.

Watching some of the Newbury broadcast from the BBC's clammy scanner truck, it's clear that Balding is a nerveless and razor-sharp operator. With one camera broken down and an interview lost, she ad-libs comfortably as the show's running order is reshuffled. She even finds time to put up suggestions to the producer once the camera is off her, begging for the "head-on shot" after one of the races looks like provoking a Stewards' Enquiry. Meanwhile, any crisis seems just to wash around Willie, as he grins disconcertingly at the camera ready to turn on the chat at a second's notice.

Clare: "And I had breakfast with Martin Dwyer this morning ... he lost a stirrup during a gallop. He's normally got a deep voice, but not today."

Willie: "He'll have a sore backside too!"

Okay, it's not exactly Katharine Hepburn and Spencer Tracy, but after years of Julian Wilson persisting with the pronunciation of "off" as "orff', it at least seems in touch with the grass roots of racing. "It's a team effort now," Carson says, "we pass the ball around a lot more."

This afternoon, the team plays abroad at the Longchamp course on the outskirts of Paris, to cover the most prestigious race in Europe, the Prix de l'Arc de Triomphe. Until a few years ago, Channel 4 had the Arc contract, and led the field with its sharp production values and colloquial style. But the Beeb has got the race back again, and can at last boast its own populist edge. Providing the public's increasing acclaim doesn't get to them - and UST doesn't set in (a safe bet) - "Clare and Willie" look like being regular winners. !