By Anthony Reuben
Business reporter, BBC News
Lord Browne resigned from BP after details of his private life emerged
Some observers say there is a "pink plateau" in British business that prevents gay people reaching its highest echelons.
BP's chief executive, Lord Browne, resigned on Tuesday after a judge criticised him for lying about how he met his former lover Jeff Chevalier.
Lord Browne had been trying to stop a Sunday newspaper printing an interview with Mr Chevalier, and has since called his sexuality a personal matter "to be kept private".
But did Lord Browne have to go to so much trouble to keep his homosexuality a secret - and would being openly gay have hurt his career prospects?
According to business magazine Management Today, there are no openly gay chief executives at companies listed on the FTSE 250 share index.
"The problem that you have in business these days is that in most other walks of life it's okay to be gay but in the top ranks of British business it isn't," said the magazine's editor, Matthew Gwyther.
"Of course there are gay men and women out there, but it's very difficult for them to admit to that and I just think it reflects really badly on us.
"There must be something that's gone wrong somewhere."
Stephen Frost, Director of Workplace Programmes at the gay rights campaign group Stonewall says: "Everyone works better when they can be themselves - it is up to all of us to support people for who they are."
'Sexist, racist, homophobic'
While there may be a long way to go, attitudes have improved in London's financial centre, the City, over the last 20 years, according to Justin Urquhart Stewart of Seven Investment Management.
"If you go back to 1986 when we had Big Bang - prior to that it was a sexist, racist, homophobic structure, which was dependent upon class," he says.
"Now there are still elements of that around, but nowhere near what it used to be like."
One of the reasons that Lord Browne may have been so keen to safeguard the privacy of his personal life was that when he started his career attitudes throughout Britain were very different.
"He came from a generation in which being a homosexual would have been extraordinarily difficult," says John Roberts, from oil and commodities analysts Platts. "He didn't grow up in an era in which it was possible to imagine coming out."
Stonewall says that many top business people who are openly gay tend to be self-made entrepreneurs.
This is often because they do not need to work within the more prejudiced environments of big corporations and as a result can be judged more fairly on their performance.
One such executive is Ivan Massow, who set up a financial services company catering especially to gay people.
"People get into such difficulties with City institutions - they're laced with people with degrees of power, stuck in these huge companies, who can really mess your life up if they decide you're a stupid poof and want to put the boot in," he says.
Another factor may have been that the oil industry in which Lord Browne worked is seen as a particularly difficult place for openly gay people to work, despite recent attempts at firms such as BP to protect and promote equal rights.
In his role as chief executive, Lord Browne would have spent a lot of his time jetting round the world talking to leaders in whose countries BP either wanted to work or already had facilities, analysts said.
That would have taken him to countries where homosexuality was not accepted and, in some cases, was illegal and punishable by death.
In such circumstances, keeping his private life secret would have been vital to Lord Browne's effectiveness as a businessman.
So Britain's gay businessmen and women may need attitudes to change elsewhere, as well as in the UK, before they can be seen heading the country's top companies.