DOWNRIGHT dangerous, discredited, stupid and irresponsible. That's the only way of describing persistent attempts by fundamentalist groups to change human sexual orientation. Well, to change gay people "straight", to be more precise.

Just days after the Melbourne's Sunday Age carried a damning expose of "reparative" treatments to Australian homosexuals, it was announced that London buses would be carrying ads advocating gay cures. Behind the ad campaign were two crackpot outfits: the Core Issues Trust (motto: God's heart in sexual and relational brokenness …) whose leader, Mike Davidson, believes "homoerotic behaviour is sinful", and Anglican Mainstream, a worldwide orthodox Anglican group whose supporters have equated homosexuality with alcoholism. The advert was due to say:

Not gay! Post-gay, ex-gay and proud. Get over it!

Such was the outrage that to the planned campaign that London Mayor, Boris Johnson immediately crushed it.

Johnson, who contacted the Guardian to announce he was stopping the adverts within two hours of their contents becoming public, said:

"London is one of the most tolerant cities in the world and intolerant of intolerance. It is clearly offensive to suggest that being gay is an illness that someone recovers from and I am not prepared to have that suggestion driven around London on our buses."

His main rival in next month's mayoral election, Ken Livingstone, said Johnson should never have allowed the adverts to be booked.