The 52-year-old model announced last week that she was separating from her fourth husband, high-powered architect Peter Cook, after a decade of marriage. The reason, it later emerged, was that she had discovered Cook had been having an affair with a 19-year-old Long Island neighbour, Diana Bianchi, who he had met when she was just 17.

The story has caused a sensation in the US, where Brinkley is seen as the iconic California girl, and has opened a debate about men in a position of power preying on their younger vulnerable staff.

Bianchi told reporters that she first met the married father-of-two while working for the summer at an exclusive toy store in the Hamptons, New York's playground of the rich and famous, two years ago.

According to Bianchi's work colleagues, 47year-old Cook was a constant visitor to the store while she worked there, flirting with her and eventually offering her a job in his architectural firm when the toy shop closed for the season. Bianchi had been hired to work on Cook's website at a rate of $50 an hour.

Their sexual relationship started soon afterwards, initiated by Cook, according to Bianchi, when he wrote on her computer screen: 'How would you feel if I told you I was attracted to you?'

Bianchi, who was 18 at the time, recalled that a huge picture of Christie Brinkley with her children hung on the wall over Cook's desk, though the architect repeatedly assured her his relationship with the model was on the rocks.

Cook also supplemented the teenager's income with gifts estimated at $1,500 a month, plus a new Nissan Maxima and frequent gifts of expensive jewellery.

The petite Southampton native, an aspiring singer, said that the strain of seeing a married man eventually became too much for her and she broke up with Cook last April.

Since then, she said, he had repeatedly harassed her with emails and calls, driving to her sister's apartment in Brooklyn, where she now lives, to place notes on her car.

The affair was discovered after Bianchi's stepfather, a local Southampton Village police officer, Brian Platt learned of the relationship through Bianchi's older sister.

Platt confronted Cook on several occasions, asking him to leave his stepdaughter alone. Eventually, a couple of weeks ago, he approached Brinkley when she was speaking at a local High School graduation and told her about the affair.

Brinkley allegedly hired a computer expert to trawl Cook's computer, unearthing several explicit emails from her husband to the teenager. She announced their separation shortly afterwards.

Bianchi, who has said she believes she was one of several women Cook seduced, has retained the services of a New York lawyer, Joseph Tacopina, who claims she has a possible sexual harassment case on her hands. "He hired her to bed her, " Tacopina has said. "He used her, abused her."

What Bianchi certainly does have is a lucrative story, and she has been making the rounds of TV and print interviews with newly acquired public relations agents since the story broke earlier in the week.

The only comment Brinkley has made is to appeal for privacy for herself and her children through her spokesperson.

The model, who was in huge demand in the late 1970s and through the '80s, was the face of Cover Girl cosmetics for an unprecedented two decades before retiring in 1996 to look after her three children and concentrate on her career as an artist. Last year, after a nine-year break, she signed another lucrative contract with the makeup company to promote their Advanced Radiance line for women over 30.

Brinkley, who was discovered as a teenager in Paris, had originally intended on being a painter.

At age 18, she went to Paris from her Californian home to study art, and married French artist Jean Francois Allaux the following year.

After they split in 1981, she began a relationship with Olivier Chandon de Brailles, heir to the Moet & Chandon champagne fortune. Chandon was killed while car racing in 1982.

In 1985, aged 30, Brinkley married Billy Joel, with whom she had a daughter, Alexa Ray, now 20, who is also an aspiring musician and painter.

Brinkley appeared in two of Joel's music videos, 'Uptown Girl' and 'Keeping the Faith', before they split in 1994, allegedly due to his party lifestyle.

Brinkley married property developer Richard Taubman the same year, but the relationship lasted little over a year. The couple had one son, Jack Paris, now 11.

When Brinkley walked down the aisle with Cook for a fourth time in 1996, it looked set to be her last. The pair had daughter, Sailor Lee, two years later and lived a quiet life on their Long Island estate, where Brinkley has become a prolific painter and photographer.