I USED to be in public relations, and now I'm a novelist, journalist and screenwriter. All my work is in the field of communications . . . that's why I admire Oprah Winfrey so much, I think she and Bono are the two best communicators in the world. I have a bit of an obsession with Oprah: I've watched the programme and read the autobiography and cried over The Colour Purplemany times.

It's well-known that Oprah comes from a very deprived background. That she has become one of the most powerful women in the world despite having the odds stacked against her from the outset is incredible.

She was born into poverty in Mississippi and suffered sexual abuse as a child. Her parents' relationship broke down and she spent some years living with her grandmother. It was only when she went to live with her father, who had a strict work ethic and encouraged her talents, that things started to come right for her.

From her teens, the thing that set Oprah apart was a natural aptitude for public speaking. Once that talent had been identified, her life began to take off. She managed to get a scholarship to college and started her broadcasting career in local radio in Tennessee at the age of 19. She went on to work as a news anchor on television and ended up in Chicago where she set up her own production company, Harpo. The Oprah Winfrey Show, produced and therefore controlled by Harpo, was a success from the word go. It has also been the springboard for other successful broadcasting careers . . . Dr Phil started on Oprah too.

I think that she is the most natural of broadcasters, her empathy with people just shines through. I admire the fact that, having achieved so much, she hasn't been content to sit on her laurels. She seems never to be satisfied, always pushing on to the next thing, using the power that she has to go further and further. I think of her as a very driven person. It was Oprah, for example, who was the prime mover behind the new child abuse laws and a register of known child abusers in the US that Clinton brought through during his term as US President. She lobbied for several years to get the legislation pushed through, motivated by the tragic experiences of her own childhood.

The Oprah Winfrey Show is broadcast in 122 countries around the world and has 49 million viewers a week in the US. When you think how many other chat shows are mediocre at best, her continuing ability to stay fresh and keep on attracting those enormous audiences is hugely impressive.

It's almost evangelical, the inspirational effect that she has on people. I know that it's easy to criticize her, she's a sitting duck in many ways because of her emotional and instinctive approach, but I think that she is a force for tremendous good in the world. I love the fact that from her own love of reading . . . she was taught to read by her grandmother at age three and has often said that reading helped her through many of the hard times in her own life . . . she has created the biggest book club in the world.

It has 900,000 members! There are also magazines, mini-series and a very successful website. The fact that she never stopped at one thing has been an inspiration to me in my own work; looking at her career in all its diversity has helped me to understand that communication is a multi-faceted skill and encouraged me not just to stick with what I know and to take on different challenges. Once someone finds out what they're good at, it's a question of staying true to that and figuring out how best to explore the various possibilities that can come from that talent. One person can do so much.

I've published three novels now and have just finished writing a fourth for Penguin Ireland. That will come out in 2007. The latest, Love Comes Tumbling, was published a couple of months ago. I'm now starting to diversify, inspired by Oprah. I've always done some freelance journalism . . . I particularly like interviewing people, finding out what makes them tick (and it's useful for the novels too) . . . but now I'm branching out into screen-writing. I've always been totally into movies . . . I loved Oprah in The Colour Purple . . . and now my novels are starting to be optioned for film so I'm gradually being sucked into that world. I recently spent some time in Italy on an Arista screenwriting course. We were in a monastery in the middle of nowhere so there was no escape! The organisers Iteamed each writer up with a producer for the week to see what would come of it . . . it was a very intense, very personal, very interesting and quite invasive experience. It was like being on Anthony Clare's couch for a week. By the time I came home I could hardly speak, it was as if I'd been knocked over the head with a hammer. Looking back on the experience with the benefit of a few weeks' hindsight I'm predicting that great things will come of it. I met a producer with whom I'm planning to work in the future.

Oprah has a strong belief in self-help, in getting people to help themselves. She uses her Angel Network to rope in other people of influence to help in dire situations like the tsunami. Bill Gates appeared on her show and she effectively door-stepped him to give money to her causes. At home in the US, and clearly propelled by the memory of her own early years, she is particularly motivated to help young women who might otherwise fall through the cracks, women who are bright but without hope educationally because of the inadequate public education system in the US.

The other quality of Oprah's that I admire is that, as a celebrity, she has managed to stay in touch with ordinary people and is socially very aware. It would have been very easy for her to cocoon herself in privilege and remain insular . . . she has not done that.

Like Bono, she uses her power to get other people to do things for her and the issues that are important to her. As a giving person she doesn't take it all from herself, and that's very smart.

Having said all this, I wouldn't want anyone to think that I spend my days glued to the television watching Oprah. In fact, we don't have a television. My daughter, Amy, broke it two years ago and we never got around to replacing it.