Veteran gay rights campaigner Peter Tatchell has “changed his mind” about a bakery that faced legal action for refusing to bake a ‘gay’ cake.

The owners of Ashers Bakery in Belfast were found guilty of unlawful discrimination based on sexual orientation and political or religious grounds, after the company in Newtownabbey, Northern Ireland refused to bake a cake showing the message ‘Support Gay Marriage’ above an image of Sesame Street’s Bert and Ernie.

Despite losing its initial case, the bakery owners are pursuing a legal appeal of the ruling – with financial and legal help from the Christian Institute.

The Christian Institute opposed the Equality Act and remains fundamentally opposed to anti-discrimination protections for LGBT people – but their case has found an unlikely ally in gay rights campaigner Peter Tatchell.

In an article for the Guardian, Mr Tatchell claimed he was not convinced the incident was a legitimate use of anti-discrimination laws, because the issue was to do with the message on the cake and not the customer’s sexuality.

He wrote: “I profoundly disagree with Ashers’ opposition to same-sex love and marriage, and support protests against them… [but] on reflection the court was wrong to penalise Ashers and I was wrong to endorse its decision.”

The rights campaigner explained: “The court erred by ruling that [gay customer Gareth Lee] was discriminated against because of his sexual orientation and political opinions.

“His cake request was refused not because he was gay, but because of the message he asked for.

“There is no evidence that his sexuality was the reason Ashers declined his order. Despite this, Judge Isobel Brownlie said that refusing the pro-gay marriage slogan was unlawful indirect sexual orientation discrimination.

“On the question of political discrimination, the judge said Ashers had denied Lee service based on his request for a message supporting same-sex marriage.

“She noted: ‘If the plaintiff had ordered a cake with the words ‘support marriage’ or ‘support heterosexual marriage’ I have no doubt that such a cake would have been provided’.

“Brownlie thus concluded that by refusing to provide a cake with a pro-gay marriage wording Ashers had treated him less favourably, contrary to the law.”

Mr Tatchell claimed the ruling set a “worrying precedent” by suggesting that “service providers are required to facilitate any ‘lawful’ message, even if they have a conscientious objection.”

In addition to opposing discrimination protections, The Christian Institute previously fought to oppose an equal age of consent for gay people, civil partnerships and same-sex marriage – while it sought to keep Section 28, a law banning the ‘promotion’ of sexuality in schools.