“If this Westminster veto succeeds, it will be the first of many.”

Nancy Kelley, chief executive for LGBTQ+ human rights organisation Stonewall said British Prime Minister Rishi Sunak was using trans people’s lives as “a political football”.

“This is the nuclear option. It is the only time that Section 35 of the Scotland Act has been used since 1998, in an unprecedented move which significantly undermines the devolution settlement and will unlock constitutional and diplomatic strife,” she said in a statement.

Strong views

The decision is likely to trigger a legal battle between Edinburgh and London, with the Scottish government previously warning it would contest what it described as any attempt to undermine the democratic will of its parliament, which has devolved powers in certain areas.

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Britain has refused to give Scotland another vote on independence, and the top UK court ruled last year that Sturgeon could not hold a referendum without approval from London.

But it is unclear whether the move by Britain to overrule the gender bill will fuel an appetite for independence, as the SNP’s own leadership is divided on the issue.

Some women’s rights campaigners have argued the changes could pose a threat to the safety of women and girls by making it easier for predatory men to access single-sex spaces such as bathrooms.

Supporters of the bill, however, said the reforms benefit transgender people and pose no threat to women’s rights.

Other countries including Ireland, Denmark and Argentina have adopted self-ID laws to make it simpler and less invasive to change gender.

“The policy area is complex and one on which most Scots are unlikely to have strong views,” said James Mitchell, professor of Public Policy at Edinburgh University.

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“If the SNP succeed in presenting this as interference then it will play into their argument for independence though it divides the SNP itself so this may not be quite as easy as the leadership hope.”