Apparently Mayor Johnson has no problems with ads by former heterosexuals, he only has a problem with ads by ex-gays.
“...Boris Johnson, the Conservative Party mayor of London, is being sued by a Christian organization whose bus advertisements for overcoming same-sex attraction he ordered pulled.
...Saying, “Not gay, ex-gay, post-gay, and proud! Get over it,” the nixed slogans were the work of the Core Issues Trust, a Christian organization that helps churches minister to those who want to overcome their temptations to homosexual behavior.
...The campaign was cleared by industry regulator the Advertising Standards Authority. It was intended to be an answer to a similar pro-homosexual ad campaign...
...Core Issues co-director Mike Davidson responded to Johnson’s action, saying, “I didn’t realise censorship was in place.”
...They okayed it and now it has been pulled.
...“It is of deep concern that there can only be one point of view and that is the point of view of individuals who are determined to push through gay marriage and apparently believe that homosexuality cannot be altered in any possible way. That is not a universally held view.”
...Johnson reacted after a chorus of rage from homosexualist campaigners, who argue that homosexuality can only ever be a natural life-long variant of human sexuality, the cornerstone of the homosexualist political schema.
...who is facing an election next month...
...The incident illustrates the growing reality that even to assert that there are some people afflicted with unwanted same-sex attraction who do not want to live the homosexual lifestyle, is now regarded as “anti-gay.”
...“On the one hand, it’s shocking, such a lack of freedom of speech, but on the other, I’m not too surprised,”...
...The climate right now, she said, is immensely hostile to anyone who opposes the homosexualist political agenda. She recounted the story of a Christian Conservative Party MP, David Burrowes, who received death threats after he signed a petition to retain the current legal definition of marriage.
...and there is growing tolerance for overtly anti-Christian rhetoric.
...“at the end of the day what it’s about is intimidation and bullying and fear” by homosexuals to silence opposition.
More/complete info here and here.