A High Court judge has ruled that Mayor of London Boris Johnson did not abuse his position as Chair of Transport for London (TfL) over the banning of an ‘ex-gay’ bus advert.

The advert, which featured the slogan “Not gay! Ex-gay, post-gay and proud. Get over it!” and was sponsored by Christian charity Core Issues Trust in response to a Stonewall advertising campaign, was banned from being displayed on London buses in April 2012.

Although the High Court ruled that the ban was lawful and in accordance with TfL’s advertising policy, earlier this year the Court of Appeal ordered Mrs Justice Lang to reconsider the case.

Core Issues Trust, and its legal representatives at the Christian Legal Centre, maintained that emails revealed by a Freedom of Information request showed that Mayor of London Boris Johnson had instructed TfL to ban the adverts, and claimed that this was an attempt by Mr Johnson to win over LGBT voters as part of his re-election campaign.

The Trust’s legal team cited an article in The Guardian which, following a briefing by Guto Harri, Director of Communications at the Greater London Authority, suggested that the decision to ban the adverts came directly from the Mayor. It also noted that Mr Johnson appeared at an election rally organised by Stonewall in the days immediately after the banning of the advert.

In her judgement today, Mrs Justice Lang ruled that the decision had been made solely by Transport for London, albeit after the Mayor’s office had given its views. She said that, although the Mayor “had statutory power to issue written instructions or directions to TfL”, he did not do so, and that she believed he “was not motivated by an improper purpose, namely, to advance his Mayoral election campaign”.

Responding to the ruling, Howard Carter, general counsel at TfL, said: “As we have always maintained, and the court has ruled, it was our decision not to run the Core Issues Trust adverts and there was no improper purpose behind our decision. Our decision was justified.”

Having lost its case, Core Issues Trust termed the ruling “a contrived and punitive judgement” and said in a statement: “Justice Lang has confirmed today that the British establishment is no longer a guardian of freedom of speech nor of conscience.”

Dr Mike Davidson, Director of the Trust, commented: “This is a clear example of the UK judiciary aligning itself with powerful political forces and personalities that will brook no opposition to the view that children are born gay and have any choice in sexual preference, expression or identity.”

He added: “Core Issues Trust supports freedom of choice and LGBT dignity but the campaign to promote homosexuality by the government, incrementally by the state church, and now the judiciary is ill-founded on notions of genetic determinism and is without uncontested scientific evidence.”