The feminist writer and national treasure Fay Weldon, the director Nicolas Roeg and Weldon’s son and film producer Dan Weldon are in a fashionable London bar, and it’s all gone a bit Carry On. They are supposed to be discussing the significance of the vaguely controversial “penetration shot” that occurs midway through their new movie, Puffball.

The film, based on Weldon’s 1980 novel of the same name, adapted by Dan (also the movie’s producer), and directed by Roeg, is about a pregnant architect (Kelly Reilly), newly decamped to the Irish countryside, who becomes the focus of local harridans (led by Miranda Richardson) who believe in extreme fertility rites and the power to pass pregnancy from one woman to another along the tip of an erect male member.

Roeg, the director of classics such as Performance and Don’t Look Now, hasn’t made a feature since the 1996 TV movie Samson and Delilah. He seems, on the surface at least, to be enjoying the limelight. Weldon, on the other hand, has been working steadily, and with increasing adulation (she is now a CBE), since her debut novel The Fat Woman’s Joke (1967). She says that all her work, including Puffball, has deep roots.

FAY WELDON I wrote Puffball when I’d just had a baby. This was 1977 and we’d just moved down to the countryside, and nothing had been written about pregnancy. Women were astonishingly ignorant about what went on. So I thought I’d write a gynaecological text-book mixed up with a novel. When it was published it aroused a great deal of hostility. It was seen as a bit fundamental, because sex and procreation had been divided and separated, and nobody wanted to combine them again. The feminists were extremely angry; they thought I’d betrayed them.

DAN WELDON I wasn’t the baby that she’s talking about – that was my younger brother Sam – but I was around when she was writing the book, and it very much filtered into the family ether.

FW But I never let my children read the books. Because I think they’re disgusting (giggles).

DW I read the opening lines of The Fat Woman’s Joke when I was 5 and I remember vividly how it was snatched out of my hand. Whereas when I read Puffball it just felt like an extension of our life. For me it eventually went from being my mother’s book to something I wanted to do, to being work.

NIC ROEG I read the script and thought, “How strange, this man writing a screenplay based on his mother’s book”. Yet there was an understanding there of life that really caught me. The film differs from the book only in superficial things, not in emotions.

FW But this idea is very new. PreSixties and pre the contraceptive pill, sex and babies were inexorably linked. Now they are not. Back then abstinence was the only secure way of not having babies. Which wasn’t much fun for anyone.

NR Every child will say, ‘Mummy, why am I here?’ Well, God knows why we are but one thing is certain, it’s to procreate. Because the root of life is in the two sexes procreating.

FW It’s why we’re together. We are a species. We get together, we have babies. The link has always been there, even in the Sixties. It just happened that there’s almost no race memory of it left. What this film is doing is bringing back the link between babies and sex.

NR But now there’s one great thing we are up against – the audience!

FW I’m not precious about it. I was never really interested in how my work was received. If it’s received well, that’s nice, but that’s not why you do it. You do it because you have some energy that drives you and doesn’t stop.

NR I never had a plan either. I just fell into it. I worked in a cutting room, putting subtitles on to French films, then got a job in the camera department at MGM in 1950. I became chief loader and took it from there.

FW Like when I worked in advertising [she wrote the famous slogan “Go to work on an egg”], television had just started so I became the television department. I’d write the script and splice the reel together all in one day.

DW I remember tripping over you writing on the stairs. You wrote everywhere.

You went out a lot during the advertising years. You had a briefcase. The success thing seemed normal to me. But then we lived in an area of London where there were quite a lot of parties. I seem to remember walking around a lot of feet. There was a lot of, well . . .

FW (giggling) A lot of carrying on!

NR Disgusting.

DW It was the Sixties! (Points to Roeg) You were probably there too! (Roeg shakes his head)

FW I did try to keep you away from all that, actually.

DW No, it was a good childhood, I enjoyed it very much. There were people like Sylvia Plath around. She threw me across a room once.

FW No she didn’t, that wasn’t her. The problem is that if you live through these days, the partying, the carrying on, they don’t seem like great days. They just seem rather glum and rather quick. You were just earning a living and getting on.

DW But it’s nostalgia for times past. Everybody searching for a root. Everything’s changing. Ideologies don’t mean anything any more.

NR This is the most exciting time of all, to be in the middle of change.

DW It’s a good time to bring out a film that stretches people’s minds and isn’t the same thing over and over.

FW It’s the same with publishing. Audiences have begun to know what’s coming next. We have to go back to people’s actual experience, their experience of being alive. It’s what matters.

NR We have to show people that we’re all parts of the same story. We’ll all go off and enact our endings differently, but our lives are all part of the one plot. We have exactly the same beginning and exactly the same end. The middle bit is just how we get there. And I love that.

Puffball is released on July 18 2008

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