PA - Professor Robert Winston

Doctor in pursuit of the divine; Wil Marlow finds the BBC's favourite man of science is also a man of God.

The health service's loss is television's gain, for earlier this year Professor Robert Winston retired from the NHS and his position as Director of NHS Research and Development for Hammersmith Hospital.

It had been a long and illustrious career in which the doctor, who is now, of course, well-known as a presenter, had made leaps and bounds in the often difficult and emotional science of fertility, helping thousands of childless couples to achieve their dream of starting a family. With such an achievement under the 65-year-old's belt, it's no wonder the good doctor is missing his lifelong vocation.

"I spent 40 years treating patients," he says, "and it's a hard thing to leave something which is so rewarding and, I hope, has been helpful and useful. It's a very nice feeling to be useful."

Robert is, of course, still making himself very useful. He continues his academic work as Professor of Fertility Studies at Imperial College, London University, and this is flexible enough to allow him to work on even bigger projects on television.

Best known for his enthusiastic and engrossing documentaries looking at human life and its history, he's become a household name and won three Baftas for series such as The Human Body, Superhuman, Walking With Cavemen and The Human Mind.

But now, for the first time, Robert is stepping out of his field of expertise for his most demanding television project yet - The Story Of God, looking at how our belief in a higher power has developed over the centuries.

Something he is keen to point out, however, is that this is not a religious programme. He looks at the story of God from a scientific and historical point of view - how people's beliefs in a all- powerful deity developed, how that belief has impacted on human development over the centuries, and how it impacts on our lives today.

"One of the reasons for me agreeing to make this series," he says, "was I wanted to show an aspect of humanity that is not, I think, very well dealt with by many scientists, who often profess strongly atheist beliefs and are rather dismissive of the spiritual side of humanity. I wanted to, as a scientist, redress that a bit really.

"It's my view, expressed in that programme, that actually there shouldn't be a conflict between science and religion, that actually they should be able to sit quite comfortably side by side. They're both looking at the natural world in different ways, but which aren't necessarily conflicting."

Robert himself is that rare individual - a man of science who practices religion, in his case Judaism. He says he's never had any trouble reconciling the two disciplines.

"I certainly follow a somewhat religious track in my life," he says. "I think religion provides a very useful framework for people and it's been quite helpful to me. Has there been a conflict between my science and religious practice? No, I don't think there has.

"On the contrary I think it's enlightened and helped my clinical practice. I think it's been very useful in making good decisions about an area of biology that is fairly controversial - mainly the embryo, human life and its start, pregnancy and conception.

"Many of the decisions I come to in helping people have been illuminated by, not necessarily my religious views, but other peoples', and religious views in general."

The professor and the BBC film crew travelled the world in their mission to tell God's story, visiting places as far flung as America, France, Switzerland, Italy, Mexico, Sri Lanka, Saudi Arabia, Iran, Israel and Egypt.

"It was arduous," says Robert. "Because it was not travelling comfortably and much of it was in quite hostile environments.

"Just getting a visa, for example, to go to India, which was what we wanted to do to film Hinduism, was extraordinarily difficult. It was so difficult that eventually we decided to go to Sri Lanka instead because it would be easier.

"In Saudi, of course, no non-Muslim can go to Mecca, which is incomprehensible really but it's there and one has to accept it.

"And in Iran it's not a very easy society to move around freely, where there are religious sensibilities and where the Shi'ite Muslims are somewhat suspicious of people who come with a Christian or Jewish or other view.

"I don't think this series would have been possible for me to do at all a few years ago when I was heavily involved in clinical practice. I regret having to leave that part of my life but life moves on and this is quite a fulfilling way of spending my life intellectually."

Robert says he will continue straying away from his usual area of expertise in future television projects -he says there's another possible philosophical series in the pipeline. But he promises to return to biology as well, he's committed to doing another series on reproduction. There's also one hugely ambitious project he'd like to take on.

"I still think that one of the great icons of television was Bronowski's 1973 series The Ascent Of Man," says Robert. "And I think it would be very interesting to revisit some of those themes from a more modern perspective.

"Whether the BBC would do that I don't know because television has changed so much and I don't want to presume they'd want me to do it anyway. "I'm always surprised they ask me to do anything, really."