KATHERINE MACALISTER gets in the mood for a chat with sex expert Dr Petra Boynton.

You know the expression ‘not now dear, I’ve got a headache”?

Well, appropriately enough, Dr Petra Boynton, one of the UK’s leading sex experts, had a migraine and we had to postpone our interview. But thankfully, a few days later, she’s ‘in the mood’ and ready to talk!

Because Dr Petra is going to be at Science Oxford to answer all your questions, and if you’re reluctant to put up your hand in public to tackle your sexual conundrums, you can write them down or email her in advance. “I’m hoping those who attend will all have questions and I’ll try and answer as many as I can, because my audience always has a lot of interesting things to talk about.”

So what do they ask? “About erectile problems, lack of desire, how to experience orgasm, pain during sex, how often we should be having sex, virginity issues – as well as the basics like how big should a penis be. Topics can also be related to enjoyment and pleasure. But people do seem to think there will be a magic solution, which is rarely true.”

Welcome to the world of Dr Petra Boynton, leading sex educator, researcher, agony aunt, wife and mother.

Although the lines between work and home are obvious to Petra, she admits others can view it differently. “Some people think I just have sex all day long,” she laughs. “Or that it’s like Sex And The City with me sitting with my laptop pondering sex. So when people ask me what I do, I say I work in international healthcare.”

Which, of course, she does, because when Petra’s not answering the nation’s sexually-related questions, she’s educating other health professionals on sexual health, and lecturing at Westminster College.

She also writes a weekly agony aunt column for More! magazine, presents a regular show on BBC Five Live, writes for the nationals and appears on TV. A busy lady.

Petra always wanted to work in family planning. She told her parents and the school careers advisor about her plans, all of whom suggested nursing instead. Yet here she is, one of the world’s leading experts. “It’s tough to be taken seriously in the world of science,” she says. “There is snobbery, but it is changing. However, sex research is a Cinderella subject, so it’s hard to get funding.”

Historically, has sex changed recently? “We think we should be more liberated because there is so much about sex in the media. That goes hand in hand with a level of unease. So there is a new sexual awareness that has influenced our lives, alongside a very basic sex education. Romance used to be the centre of a relationship, but now we think lots of sex is the key, so there are more questions about addiction.”

But why the Science Oxford talk? Are we particularly deficient in the bedroom? “My aim is to talk about why we need relationships research, where there are knowledge gaps, and how we can learn more about our relationships,” the 40-year-old says.

Is she expecting lots of back row tittering? “I was teaching a bunch of surgeons last week and they were all giggling,” she admits. “The teens tend to be more mature. Of course, sex can be funny. But not to the point where we denigrate other people’s problems.”

So does Petra ever get embarrassed? “My four year-old son asked to see my willy on the bus – so I’m not immune,” she laughs.

* To celebrate its 5th birthday, Science Oxford is bringing back favourite events from the past five years, including world’s leading nutritionist Prof Jeya Henry; anthropologist and evolutionary biologist Prof Robin Dunbar; Roy Overall’s 48 years of research into swifts; Dr Ian Griffin’s stargazing session in South Park; physics Prof Brian Foster and violinist virtuoso Jack Liebeck performing a night of music and science with Einstein’s Musical Universe; and Prof Charles Spence talking abour experimental psychology.

Visit science oxfordlive.com for more details.

* Dr Petra Boynton, right, will be at Science Oxford next Thursday. You can email questions in advance to her at info@ drpetra.co.uk