Boris Johnson's LGBT+ business champion has resigned over the "profoundly shocking" failure to ban conversion therapy for transgender people.
Iain Anderson, who was appointed last year, said trust in the Government's commitment to LGBT+ rights has been damaged after chaos over its promised ban on the vile practice.
Mr Johnson did a chaotic double U-turn when a leaked document revealed he was abandoning the Tory pledge to ban trying to “cure” people of their sexuality.
In the face of widespread anger, sources then told ITV News Mr Johnson would go ahead with the ban - but excluding transgender people.
At least 100 organisations have pulled out of the Government's upcoming LGBT conference in protest.
Mr Anderson said it had been the honour of his life to serve as the UK's first LGBT+ business champion, but felt he had "no choice" but to resign.
In a letter to Mr Johnson shared on Twitter he wrote: "As a young gay man I lived through fear and oppression under the backdrop of Section 28.
"I could never have dreamt then that a government - any government - would appoint an LGBT+ champion later in my lifetime.
"However the recent leaking of a plan to drop the Government's flagship legislation protecting LGBT+ people from conversion therapy was devastating. Conversion therapy is abhorrent.
"Only hours later to see this plan retracted but briefing take place that trans people would be excluded from the legislation and therefore not have the same immediate protections from this practice was deeply damaging to my work."
Mr Anderson added that it was "profoundly shocking" that the Government had backtracked on protection for transgender people during the same week that the first trans MP felt able to share his journey.
Jamie Wallis, Conservative MP for Bridgend, last week came out as trans in a highly personal statement.
The 37-year-old tweeted it was "wrong to exclude protections for a whole group of people from a practice described as 'abhorrent"'.
He argued that it would be a "broken promise" to allow conversion therapy to be banned, but for it not to apply to trans people.
A government spokeswoman said: "We thank Iain for his contributions as LGBT Business Champion.
"The Government has a proud record on LGBT rights and we remain committed to building upon that work with sensitivity and care."
