Image copyright Getty Images Image caption Lord Browne quit as head of BP in 2007 when details of his personal life were revealed

Lord Browne, the former chief executive of BP, is urging companies to do more to end discrimination against homosexuals.

Speaking at the launch of Connect Out, a lesbian, gay, bisexual and transgender network set up by Arup, the engineering and design consultants, he said: "My sense is that the business world remains more intolerant of homosexuality than other worlds such as the legal profession, the media and the visual arts. I am one of a handful of publicly gay people to have run a FTSE 100 company.

"In some industries, the situation is particularly bad. Among the many people I know in private equity, where I now work, fewer than 1% are openly gay."

He therefore wants "leaders in companies, and not just in human resources" to "think about inclusion in every decision they take". He says: "It comes down to a simple maxim - don't do anything that excludes people."

And he feels that change requires "rigorous performance measurement", the establishment of "concrete targets".

Lord Browne, who has never before spoken publicly about sexuality in the workplace, says it can be what he describes as "the smallest things" that can discourage gay people from being open with their colleagues about their sexuality.

"It is things like homophobic jokes that you somehow get used to, but never accept. Or it's the conversational assumptions about spouses and children. Perhaps, even, it's the games of golf at the weekend."

Media playback is unsupported on your device Media caption Lord Browne: Being gay in the business world in the 60s was a little grain of personal terror

It was not until the end of his 41-year career at BP that he came out. Looking back on it, he says: "Hiding my sexuality did make me unhappy and, in the end, it didn't work. People guessed, and it was only a matter of time before it came out. I realise now that the people we dealt with certainly knew I was gay. Putin had files on everybody. But at the time I was trapped by the fear of exposure."

He goes on: "In fact I was trapped for most of my adult life, unable to reveal who I was to the world. I led a double-life of secrecy, and of deep isolation, walled off from those closest to me."

Just over five years ago, Lord Browne quit as BP's chief executive in painful and humiliating circumstances. He admitted that he had lied to a court about the circumstances in which he had met a former boyfriend.

He told me, when I interviewed him on Tuesday, that he had got so used to lying about his sexuality that he didn't think through what he was doing when he misled the court.

Lord Browne points out that when he first realised he was gay, in 1960 at boarding school, homosexuality was illegal, though the law was abolished when he went to Cambridge.

He says: "After Cambridge, when I joined BP as a graduate, it was immediately obvious to me that it was unacceptable to be gay in business and most definitely the oil business. It was a very macho and sometimes homophobic environment; I felt I had to conform."

Also, he did not want to upset his Jewish mother, who had been in Auschwitz: "My mother, whom I dearly loved, rejected any discussion of my sexuality. With her background of being persecuted she was sure that the same would happen to me."

Lord Browne believes the UK has a duty to promote sexual and gender equality internationally.

"Homosexuality remains illegal in more than 70 countries. In seven countries, it can carry the death penalty. That injustice is primarily a British export, shipped abroad in the days of the empire. In my view, we should be working overtime to correct it."