Top firms can boost the number of lesbian, gay, bisexual and transgender business leaders by introducing gender board quotas, according to Natalie Bennett.

The Green leader told IBTimes UK that by implementing the positive discrimination measures for women, businesses will "naturally" look beyond their "golf club" mentality to employees from the LGBT community.

"I think what happens, and there is quite a lot of evidence of this internationally, is [that] when you actually bring in quotas for women, you open up to more diverse groups of people," she said. "Once you are looking beyond the members of the golf club, you end up with more diverse boards."

The UK does not have quotas for LGBT or female directors but Lord Davies's review into female representation on FTSE 100 boards found the number of women directors nearly doubled between 2011 and March 2015.

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The research revealed female representation had surged to 23.5% in Britain's top companies and found there were 365 women board members at FTSE firms.

However, Davies also revealed female representation on FTSE 250 companies was at 18% in March.

Elsewhere, Christopher Bailey was the first CEO in the FTSE 100 to be openly gay when he became the boss of Burberry in 2014.

Across the Atlantic, Tim Cook became one of the world's most well-known LGBT business leaders when he was named the CEO of technology giant Apple in 2011.

The comments from Bennett came after she unveiled the Greens' LGBT manifesto in Soho, London.

"Homophobia, transphobia and biphobia are still all too common in our society. Too many people still fear persecution – at home, in the workplace and on the street," she warned.

"In parliament the Greens' Caroline Lucas has been a tireless advocate for equal rights. She led calls for LGBTIQ-inclusive sex education, and fought against loopholes that meant that same-sex spouses did not receive equal pension rights.

"And our promise to the LGBTIQ community is that a strong group of MPs will always work with you, and fight for your rights. We know that the struggle continues – and we'll do everything within our power to work with you towards ending discrimination."

The launch came with just six days to go before the general election, with Bennett's party on just 4% in the latest opinion poll from Populus.