Women are still in a minority in the oil and gas sector, making up only around 20 per cent of the entire workforce, but a growing number are reaching senior positions and helping others to follow in their footsteps. We talk to three women who have broken through the glass ceiling.  LOUISE KINGHaM 40, chief executive of the Energy Institute  Louise Kingham, OBE FEI, has been chief executive of the Energy Institute for the past eight years. She previously headed up the Institute of Petroleum and the Institute of Energy.  "I didn't expect to go into this field when I was studying for my original business degree in Design and Media Management at Ealing College of art. But then I was given the opportunity to do some marketing and development work for the Institute of Energy and I was hooked. Energy is fundamental to life and affects societies everywhere. Whether you are involved with domestic supply or interested in global energy policies, there is no likelihood of ever getting bored.  "I haven't got enough digits to count off the number of times when, in my early days as a chief executive, at the age of 27, I was mistaken for my own personal assistant and expected to bring the coffee. But that's history, and things have really changed for the better over the past 10 years or so. There are now quite a few women in senior roles here at the Energy Institute.  "I have been on rigs in the North Sea, and attitudes have shifted there too, in my experience - away from a macho culture to one that is very accepting of women. The last time I made a visit, a team of women from angola were there, training to be operators on oil rigs back home. They were warmly welcomed.  "I think there is now a problem with perception rather than reality for women working in the oil and gas sector. It is our job to make sure that women realise this sector needs their talents, on their terms. I have two small children, aged five years and 18 months, and I have remained in my post thanks to flexible working. It's perfectly possible to have both a family and a career in the energy sector, if that is what you want.  "In my experience, more women are coming into this sector because they are concerned about issues such as climate change, and they want to be part of the solution. But I don't think they want to be singled out for special treatment through quotas and targets. They hope to make it on their own merits, and there is no reason why they can't go right to the very top."  RUTH CaIRNIE age undisclosed, vice president, group strategy and competitive intelligence, at Royal Dutch Shell  In her current role with Royal Dutch Shell, Ruth Cairnie is based in The Hague. Previously, from 2005 to 2010, she was responsible for Shell's global Commercial Fuels business. She is also the mother of four grown-up children.  "I joined Shell Research straight after leaving the University of Cambridge, where I had been doing research into cosmology and black holes. I had previously graduated with a joint-honours degree in mathematics and physics from the University of Bristol. I was looking to continue doing high-quality research, but with a more practical application, and Shell Research was right at the cutting edge in what I wanted to do.  "It was a very male-dominated working environment at Shell Research back then, but I was used to that, having studied physics at university where women were in the minority. Throughout most of my career I have been the only woman in the team. It is only recently, over the past five years, that I have found myself working more often in teams with other women. But it hasn't made a difference to how I have been accepted or made to feel included in the workplace. I have always felt valued and able to contribute in the fullest possible way. Indeed, next month I take over as executive vice president, with overall responsibility for Shell's strategy and planning at group level.  "In terms of the battle for talent, we do need to ensure that we offer an attractive work environment for women and for those with different backgrounds. Diversity in the workplace makes for much more robust decision-making and aids a better understanding of our customer base.  "It's important to get the next generation of women seriously considering oil and gas as a career option. In my role as an ambassador I visit universities to talk about my experiences