Boris Johnson has a "blind spot" when it comes to appointing LGBT+ people to his top team, the UK's first openly gay cabinet minister has suggested.
Lord Chris Smith, who was a member of Tony Blair's first cabinet in 1997, said it was a "matter of great regret" that there were currently no out cabinet ministers.
He urged the PM to diversify his top team in "the next year or two".
A government spokesman said Mr Johnson was committed to improving diversity.
The UK parliament now has its highest ever proportion of lesbian, gay and bisexual MPs, including two non-cabinet ministers, although there are no openly transgender members of parliament.
Lord Smith, who was also the first openly gay male MP after coming out in 1984, said electing a trans member of parliament was a "glass ceiling" yet to be broken.
"In terms of lesbians and gay men I think the glass ceiling in Parliament has well and truly been broken," he said in an interview to mark LGBT+ History month.
"The glass ceiling in the cabinet has been broken by quite a number of us over the years. Sadly at present they seem to want to put it back in again."
Chris Smith's career
- A leading figure in New Labour, who became an MP for a North London constituency in 1983
- The following year, at a gay rights rally in Rugby, Warwickshire, he said: "My name is Chris Smith. I'm the Labour MP for Islington South and Finsbury, and I'm gay"
- Smith's unscripted announcement - which earned a standing ovation - was the first time a gay MP had chosen to come out
- Labour's Maureen Colquhoun - a pioneering feminist whose death at the age of 92 was announced earlier this month - had been open about her sexuality in the 1970s, after the Daily Mail revealed she was in a relationship with another woman
- In 1997, Smith was appointed culture secretary, with responsibility for the Millennium Dome, the creative industries and introducing free museum entry
- He later served as head of the Environment Agency, after stepping down as an MP in 2005 and entering the House of Lords
Justine Greening who was the first and, as things stand, only out lesbian cabinet minister thinks it's more of a "pipeline" issue - that not as many LGBT+ MPs have risen through the ranks as had been hoped.
Ms Greening served in Theresa May's Conservative cabinet, as education secretary and equalities minister, alongside Secretary of State for Scotland, David Mundell, who also came out while in office.
"There wasn't maybe quite that level of a pipeline behind us that maybe we'd hoped for," said Ms Greening.
"I think having people from all walks of society really really matters and I think that's how you get better decision making."
Lord Smith said that having LGBT+ people in high office sends out a "positive message" that "this is something to be proud about, to be open about, to feel confident about being yourself".
The peer and former Labour cabinet minister claims Boris Johnson's main priority in choosing his first cabinet was to ensure they were on board with his Brexit policy, but he says the PM should now cast his net wider.
He urged Mr Johnson to "look to the greater talent that is out there and it will include some people who happen to be lesbian or gay".
Justine Greening, who also campaigns on social mobility, said that the government has had "an exceptionally challenging time" tackling Covid but, she suggested, a future reshuffle could be a time for change.
"Hopefully… as the vaccine progresses… we can look to a life almost beyond and I think it's that moment then that there's a big debate to be had about not just levelling up but how do you make Britain a fairer place."
A government spokesperson said the prime minister was "immensely proud to live in a country that is one of the most progressive and liberal when it comes to LGBT equality",
"The UK government is proactively working with other countries to improve LGBT rights internationally" they added.
"The PM has committed to doing more to make sure the government fully represents the people it serves."