Uh oh, uh oh…

Michelle Obama told me she was happy her girls have someone like me to look up to

IN 2006, Beyonc Knowles gave an interview to Forbes magazine. "I've worked too hard and sacrificed too much to do something silly," she told the financial publication. "That would mess up the brand I've created all of these years."

Yet several minutes of grainy footage, shot on a mobile phone on New Year's Eve at the private members club Nikki Beach on the exclusive Caribbean island of St Barts and posted on YouTube last week, suggests something silly is exactly what she has done. With her long, corkscrewed hair flowing over her shoulders and her famous curves encased in a skintight leotard, the camera shows Knowles working the crowd in a hot and tiny venue. She shimmies, she prances, she bodypops, delivering a flawless performance to an audience of the the beautiful and the rich, which included the party's host, Mutasim-Billah Gaddafi, son of the Libyan leader Colonel Muammar Gaddafi.

The performance has provoked outrage, with critics demanding to know why the R&B songstress was performing for, not to mention receiving a hefty amount of money from (as much, it is rumoured, as $2million), the notorious playboy son of a dictator. It is a rare wrong move for a woman who, at the age of 28, has worked slavishly hard to build herself into a modern-day icon, the world's fourth most influential celebrity (according to Forbes) and the ultimate good girl. As she confessed to a magazine after performing at Barack Obama's inauguration in January last year: "(Michelle Obama] told me she was very happy that her girls have someone like me to look up to."

Brand Beyonc has its origins in the Texan city of Houston, where the young Knowles was brought up in a deeply religious middle-class family. Her father Mathew, a Xerox salesman, drove her career from an early age, when Knowles showed musical promise and a rounded, mature singing voice. By the age of eight she was auditioning for girl groups and won a role in a band named Girls' Tyme, along with Kelly Rowland, who would go on to become one of her bandmates in Destiny's Child.

Soon, Mathew Knowles was getting involved in the management of the group, and in 1995, when Knowles was 14, he quit his job to become the band's full-time manager, establishing a hothouse, bootcamp approach to the girl group – who now numbered four. They would practise all the hours of the day, often rehearsing dance routines in their backyards or in Knowles' mother's hairdressing salon and perform in churches and town halls. Her mother, Tina, designed the girls' costumes, but it was Mathew, who still manages his daughter today, who was in charge.

Even now Knowles is reticent about her relationship with her father – although she did reveal recently that she argues with him more than anyone else she knows. But she has admitted in the past that the amount of control he had over her life meant that their relationship was fractious when she was younger.

"It took a while for me and my dad to have an understanding," she once said. "When I turned 18 and started handling my business more, he went into shock. And we had our issues. I'd say 'No' to something, and he'd book it anyway. Then I'd have to do it because I'd look bad (if I didn't]. We would fight sometimes, and it took about two years, to when I was 20, for him to realise, 'Oh, she is an adult now, and if she doesn't wanna do something, I can't make her do it.'"

Destiny's Child, targeted at the 13-30 female market, released their eponymous debut album in 1998 to rapturous applause. Here was a fresh, funky and black girl group that appealed to young women of all races. The band released a string of hits, many of them empowering women anthems, but while they were, in name at least, a girl group, it was clear that there was only one star – Beyonc Knowles. With her father in charge, the line-up shifted several times after they made it big (which resulted in a number of messy court cases involving former members) and Knowles appeared in the centre of the trio in every performance, video and photograph, making it clear that even though Destiny's Child were to have enormous success – going on to become the most successful girl band of all time – the band would ultimately act as a launching pad for Beyonc's solo career.

Unlike peers such as Britney Spears, who had a highly publicised breakdown two years ago, Knowles is known in the industry as the consummate professional – always on time, always polite, always co-operative and ready to work. She describes herself as a perfectionist, and "boring". Clothes designer Thierry Mugler, who she works closely with, gushed recently: "She speaks highly about her fans. She does not want to disappoint them. She acts as if she had an appointment with them that she does not want to miss."

In 2003, she met the rapper Jay-Z. A phenomenally successful hip hop artist and businessman (he calls himself the CEO of hip hop) with a string of projects which includes his own line of clothing, restaurants and a record label, Jay-Z, who was born Shawn Carter, is a former cocaine dealer from a housing project in Brooklyn, New York. The two released a single together, 03 Bonnie & Clyde in 2002, and he went on to rap on her breakthrough solo single Crazy In Love.

The couple are immensely private – for years denying they were an item and, when they finally married in April last year, refusing to confirm the fact for months. It is a remarkable feat in today's celebrity saturated world.

"Jay doesn't get involved in my business and I don't get involved in his," she said once. "He was very successful before I met him and I was very successful before I met him. So we have so much respect for each other, and respect for each other artistically. We are very close friends, and I believe he is the ultimate artist and he has the same feelings for me."

The pair are believed to be worth close to $1 billion, and are ranked by Forbes as the highest earning Hollywood couple. The fact that Jay-Z knows the Clintons socially and is also a friend of Barack Obama ("We're pretty friendly, but we haven't played basketball yet. We will shoot some baskets 'cause I wanna see where he's at with that," he remarked about the US president recently) has placed the couple at the top of new American power lists.

All of which makes Knowles's decision to perform for Gaddafi even more perplexing. For all that Knowles – who boasts a performing alter-ego styled Sasha Fierce – projects a slick, professional 21st-century image, perhaps this latest move is proof that even women who describe themselves as a "brand" are capable of doing something that can easily soil a good name.