The failure of the Government to deliver on its previously-promised pledge to ban conversion therapy has been branded “an act of frightful negligence”.

Campaigners had been hoping to hear mention of a Bill on the matter in the King’s Speech.

The ban was first promised by Theresa May’s government in 2018, before it was downgraded to not include transgender people by Boris Johnson.

Rishi Sunak’s Government said in January it would ban conversion therapy for “everyone”, including transgender people.

But while describing the practice as “abhorrent”, the Government has previously added that it is still “carefully considering this very complex issue”.

Following the King’s Speech, which made no mention of such a Bill, LGBTQ+ group Stonewall said those affected by conversion therapy practices “deserve better”.

Asked about a ban, a spokesman for the Government on Tuesday reiterated that the issue is “complex” and said it is “important we don’t do anything that has unintended consequences in our approach”.

Robbie de Santos, director of external affairs at Stonewall, said: “The UK Government’s failure to deliver a ban on conversion practices after five years of promises is an act of frightful negligence – in doing so, it has given the green light for the abuse against LGBTQ+ people to continue unchecked.

“Rather than getting mired in a cynical cultural war, the UK Government should be making decisions based on what the evidence and expertise said.

“England and Wales’ 1.5 million LGBTQ+ people, and their families, deserve better.”

NHS Providers, which is the membership organisation for NHS trusts in England, said it is “deeply concerned by the omission of a ban on conversion therapy”.

Its deputy chief executive Saffron Cordery said: “This was a chance for the Government to use the full protection of the law against any risk of widely discredited, dangerous and discriminatory practices against the LGBTQ+ community.”

The Royal College of Nursing echoed this, saying the lack of mention for a conversion therapy ban was “bitterly disappointing”.

Chief nurse, Professor Nicola Ranger, said: “It’s been five wasted years of hollow promises to ban these abhorrent practices that nursing staff know have no medical basis.”

Conversion therapy practices seek to change or suppress someone’s sexual orientation or gender identity.

Asked why banning conversion therapy is not a priority for the Government, the Prime Minister’s official spokesman told reporters: “I think so-called conversion therapy is abhorrent.

“The approach to ensuring it cannot take place is a complex one and it’s important – as has been highlighted by others – it’s important we don’t do anything that has unintended consequences in our approach.

“That’s why we are taking the time to carefully consider what is right before setting out the next steps.”

Labour has pledged to introduce a “no loopholes” trans-inclusive ban on conversion therapy if elected.