THERE'S a persistent and widely held assumption about high-flying women that, somewhere along the line, a choice has to be made between career and family.

If that's true, no-one appears to have told Lesley Yellowlees. At 58, the professor of inorganic electrochemistry at Edinburgh University is not only a vice-principal and head of the school of science and engineering, but she is also president-elect of the Royal Society of Chemisty (RSC), the first woman to hold the post in its 170-year history. She becomes president this month. It is a hugely prestigious accolade, making her part of a global scientific elite.

Walking into her office, however, all you see is evidence of her other, even greater passion: her family.

Beside her desk is a wall-to-wall gallery of her relatives and friends, each one blown up to A4 size. They smile down on visitors like a jolly welcoming committee. She gives me an enthusiastic guided tour. "This is me and my two sisters, Heather and Morag," she says, pointing to a picture of three smiling women, huddled up close, "and this is my husband Peter and his brother David who lives in Australia. Oh, and that's me on the Great Wall of China. That's my mum and that's my son Mark and my daughter Sarah."

It all conveys a strong sense of Yellowlees's priorities. "Family are hugely important and my friends as well," she confirms emphatically. "You've got to have support outside, you've got to, because work isn't always going to go well."

So close is the family that Yellowlees, her mother and sister Heather, have opted to live in the same Edinburgh suburb, Fairmilehead. With both of her children living nearby too, every Sunday evening, everyone, sometimes including sister Morag from Glasgow, gets together for a meal.

All this family love and support is the ballast to a professional life that is relentlessly busy. It will be 6pm when we finish, but Yellowlees still has another event to attend. How does she fit everything in?

"With a heck of a lot of help and support," she says, laughing uproariously, looking at her PA Gail.

"With difficulty," adds Gail, whose daunting task it is to juggle the demands of her boss's three jobs.

So Yellowlees has her share of stress. It quickly becomes clear, however, that she is someone whose default setting is upbeat. Even when considering her answer to a question about chemistry, the smile plays around her lips. And then there's her laugh, a head-back, eyes-closed, body-rocking giggle that erupts at the end of sentences and often half way through them. It gives her a likeable air of never quite taking anything completely seriously.

Of course, she does take things seriously, particularly chemistry. A bent for science and maths runs in the family. Her late father studied physics at St Andrews and then maths at Cambridge, but gave up his PhD to go into industry with Hedley's in Newcastle, a soap-making firm owned by Proctor & Gamble. Yellowlees retains remnants of Newcastle pronunciation even now.

Then when she was nine, her father got a job managing a Rank Hovis McDougall bakery in Edinburgh, and the family moved to Morningside.

For the next few years, cakes were on tap, thanks to dad, and science became Yellowlees's passion, thanks to her "wonderful" teachers at St Hilary's all girls school (now a residential care home). "I liked the mathematical aspects of physics and chemistry, which is why I did chemical physics when I went to university."

Going to university in Edinburgh in the early 1970s, she was one of only two women in the class. By the time she reached her honours year, she was the only one.

Yet she says it didn't daunt her to be the only representative of the female gender among either lecturers or students. "I enjoyed the course enormously so I think if you enjoy what you're doing and you're doing it well, that's what's important."

She enjoyed it right up until graduation; and then, to the enormous surprise of her tutors, she decided she hated science and gave it up to become an NHS administrator. Why?

She shrugs. "I had just had enough, of science, and of studying, probably. I wanted to try something else.

"But I can remember having a viva for my degree and the guy asked me what I was going on to do next. I said I was going to work for the NHS and he said, 'I'll bet you you're back doing science before very long.' And I wish I could meet him again and say, 'You were right.'"

After a year, she realised she'd made the wrong choice. So, after getting married and moving to Australia with her new husband Peter, a chartered accountant ("he allowed me to be an academic with expensive tastes"), she started doing solar energy research. When the couple returned to Edinburgh two years later, for Peter to take up a new job, she started a PhD in electrochemistry (studying the transfer of electrons to or from a compound).

A post-doc, lectureship, hard work and promotions followed so that now she has an office at the King's Buildings science campus that is plain and modest but has a view on to Blackford Hill that would befit a stately home. As we chat, a pheasant struts across the grass outside.

She is saddened to have had to give up teaching, which she loved – the regular international travel to conferences and meetings meant something had to give – but becoming RSC president is the realisation of a long-held ambition. As the first woman post-holder, she is making history. How did it feel to receive the news? "It just made me feel humble," she says, "but really proud that my peers felt I could do it. It's a wonderful ego booster."

The advancement of women in science is her theme of office. She made headlines with a speech in May in which she noted that Britain was half a century behind the United States when it came to the number of women in senior academic positions.

Research shows only 27% of Scottish women trained in science, technology, engineering and mathematics (Stem) subjects are pursuing a career in the field.

At undergraduate level, there is gender parity. "But unfortunately by the time you get to professor at university, it's down to 6-7% that are women. Of all the Stem subjects, chemistry's the worst."

She hurries to her desk where she rummages around for a line graph showing how drastically the numbers fall. "See, look," she says, adding with jokey ferocity, "Take that off my desk, I don't like it."

There are several reasons for the lack of women at the top, she believes, such as bias by male recruiters and the lack of a sustained campaign to encourage more women to stick with science. The "long hours culture" and the fear among women they can't do senior jobs could also be part of it, she speculates.

So inevitably, she herself has become a role model. She is regularly asked to mentor other women.

"People tell me, 'You have to do it, Lesley, because we need more women with children who have tried to have a successful career and successfully brought up a family,'" she says, then adds with a smile: "Probably you'd argue I had had the successful career; whether I've been successful in bringing up my children, you'd have to ask my children."

She looks faintly uncomfortable when asked if she herself has ever been discriminated against on the grounds of her gender. "I am naturally a very positive person so I don't really like to stop and dwell on things like that. If pushed, I could think of several times when that's happened, but I'd much rather think of all the times I've had support and been encouraged."

It's an answer that belies a sort of negativity-blindness that might help to explain why she has progressed through the ranks where some other talented women have not.

Another significant reason for her success, however, as Yellowlees is at great pains to stress, is that she has had lots of help, not just from colleagues, but from her support staff and her family. When her children were younger, her parents were always on hand. "If I were doing an experiment, for example, and I couldn't leave work, my mum would give them their tea," she explains. "My children thrived with my mum and dad. They were endlessly patient."

Her daughter Sarah, an actuary, is now 27, and her son Mark, who is training as a chartered accountant, is 25. She no longer has to rush home at nights, but nevertheless guards her leisure time jealously. She and Peter spend two fortnight-long holidays each year at Kenmore and Ballater, and she has several pastimes and interests. She lists them as walking, cooking, golf and – in all seriousness – laughing.

"Luckily I'm blessed with great friends who help me laugh," she says, "and I do think it's a great recipe for all ills."

On cue, she bursts out laughing.

lesley yellowlees, professor and president-elect of the royal society of chemistry