Over the course of my career at BP, from trainee to chief executive, I was frequently asked whether I had a girlfriend or whether I was married. People assumed that I was a bachelor who had not yet met the right woman. It was a fair assumption, for an obvious reason: Most people are straight. But for those who remain in the closet, the assumption of heterosexuality can be highly damaging. It reinforces their feeling that being gay is something out of the ordinary, something that would put them at a disadvantage in their personal and professional lives, and something that is probably best kept hidden.

The assumption of heterosexuality is one of the reasons that many people in business and in other sectors continue to lead hidden lives. I have spent the past 18 months conducting interviews for my book, The Glass Closet: Why Coming Out Is Good Business, about the risks and rewards of coming out in business. I encountered men and women who, despite living in an age of diversity targets, lesbian, gay, bisexual and transgender corporate networks and equal marriage, are still afraid of the consequences of coming out. Young executives in their 20’s should be free of the fears that plagued me for over 40 years, but the evidence suggests that many of them are not.

Through four decades at BP, I kept my private life separate from my business life. As a young professional in the oil industry, my career was going in the right direction, and I saw absolutely no purpose in coming out. The corporate ladder was slippery enough on its own, without complicating things by throwing oil on the rungs. By the time I was chief executive, I was worried that any disclosure would damage critical business relationships, particularly those in the Middle East. In countries where homosexuality is illegal, my public profile probably would have protected me, but my sexuality could have had unknown and unlimited consequences on BP’s businesses.

Looking back now, and with the enormous benefit of hindsight, I wish I had been brave enough to come out earlier. The reactions of friends and colleagues have shown that my worst fears would not have come true. But my desire to keep my private life led me to make some terrible errors of personal judgement, and I had no choice but to resign from the company that had structured my entire professional life. I was not a victim, and I made some bad choices that had traumatic consequences.

It is the responsibility of the LGBT minority to overcome their fears. Only they can decide to live a unified private and public life. But only straight people can create the environment of acceptance, understanding and inclusion, which makes that decision easier. In my experience, and based on the evidence I gathered while writing The Glass Closet, there are three things which the straight majority can do to transform the lives of the LGBT minority.

The first is for straight leaders to set a clear direction from the top. No matter how diverse and open an organisation might be, leaders should not underestimate the importance of simply talking about LGBT inclusion, as it sets the context for everything else you do. Chief executives who take LGBT inclusion seriously make time to broadcast their beliefs. It is increasingly noticeable when they do not.

But well-meaning speeches do not create sustainable actions. The second step toward full inclusion is to ensure that positive messages are accompanied by meaningful solutions. That begins with policies to ensure that LGBT people receive equal treatment. Granting the same company healthcare benefits to same-sex couples as to heterosexual couples might seem like an obvious step, but one-third of Fortune 500 companies still fail to do so. Equality and inclusion requires straight leaders to think beyond the structures, which have traditionally defined the way companies operate.

The third thing that the straight majority can do is create and participate in programmes which encourage straight employees to give their support for LGBT inclusion. Usually known as ‘allies programmes,’ these groups do not require a lot of effort, courage or creativity. They are simply a way for straight people to signal their support for LGBT colleagues, and to learn how best to make those colleagues feel comfortable bringing their whole selves to work. These groups are most effective when they make a conscious effort to stamp out ‘micro-inequalities,’ such as the assumption that every man is married to a woman, or the practice of not asking gay people about their partners in case it makes them feel uncomfortable. These are small gestures, but the signal they send to someone in the closet is enormous.

Only the heterosexual majority can make these changes. Implemented uniformly and consistently, they can create the inclusive environment which enables employees to be themselves at work. But individuals must then take their careers into their own hands. While writing The Glass Closet, I came across examples of LGBT people who have taken a risk, gone against the advice of colleagues, or shown immense courage in order to make a difference. I tell their stories so that they can be shared, celebrated and emulated, in the hope that they inspire others to do the same.

I hope that The Glass Closet will make it easier for the LGBT minority to make the right choices, and to devote all their energy to living a unified private and public life.

Lord John Browne is a former CEO of BP, Author of the Glass Closet: Why Coming Out is Good Business and the founder of glasscloset.org an online resource.