The Foreign Office has issued a formal apology for its historical discrimination against LGBT staff, including the refusal to employ gay diplomats.
Sir Philip Barton, the most senior civil servant at the department, admitted on Monday that it was a “misguided” approach that had deprived Britain of some of its “brightest and best talent”.
The public apology came 30 years after the ban on LGBT staff was officially lifted in July 1991.
The policy prior to that had been based on a suggestion that gay and lesbian staff could be more vulnerable to blackmail due to their sexuality, potentially posing a security risk.
It was a fear fuelled by spy scandals such as the case of John Vassall, a clerk at the British Embassy in Moscow who was caught in a gay honey trap sprung by the Soviets. He was blackmailed into passing secrets to the KGB and consequently jailed for 18 years in 1962.
The move by the Foreign, Commonwealth and Development Office to say sorry came after GCHQ issued a public apology in 2016 for its “horrifying” treatment of homosexual spies such as Alan Turing, who were hounded out of the service.
Sir Philip, head of the Diplomatic Service, said in a message to all staff on Monday that it had been wrongheaded to believe that LGBT people were at greater risk of blackmail that their heterosexual equivalents.
He said: “The ban was in place because there was a perception that LGBT people were more susceptible than their straight counterparts to blackmail and, therefore, that they posed a security risk.
“Because of this misguided view, people’s careers were ended, cut short, or stopped before they could even begin. And the diplomatic service undoubtedly deprived itself of some of the UK’s brightest and best talent.
“I want to apologise publicly for the ban and the impact it had on our LGBT staff and their loved ones, both here in the UK and abroad.”
A video of the apology message was posted on the Foreign Office Twitter account.
Dominic Raab, the Foreign Secretary, paid tribute to gay staff, expressing his gratitude to the UK’s “LGBT diplomats, past and present, who so brilliantly represent our country and promote our values around the world”.
He added: “As co-chair of the Equal Rights Coalition (ERC), we are working with 41 partner countries to tackle discriminatory laws and prejudice globally.
“The UK champions LGBT rights because we believe freedom and tolerance are a source of strength in communities at home and abroad.”
Britain is set to host a two-day conference of the ERC, an intergovernmental group of 42 nations, starting Tuesday, which is due to launch a new five-year strategy to protect and promote LGBT rights.