A SERIES of Unionist politicians have lined up to intervene after the Scottish parliament voted for gender reform, with a key divide emerging on how it will impact on the future of the UK.

Theresa May, the former Tory prime minister, has come out in support of the Gender Recognition Reform (Scotland) Bill, saying she is disappointed that similar legislation is not being considered in England.

She also suggested that efforts from the UK Government to invoke Section 35 of the Scotland Act and block the bill from becoming law – something Scottish Secretary Alister Jack has suggested he is considering – would fuel support for Scottish independence.

READ MORE: MP says UK Tories opposing gender reform may 'help Scotland get independence'

“We have different legal systems,” May told BBC Radio 4. “Obviously, there’s a different system in Scotland, but I think it is important when any part of the UK is looking at legislation that only affects that part of the UK, that thought is given to what the impact would be on the Union.”

Public law professor Aileen McHarg said it was an “interesting intervention” from the former Tory leader.

“It underlines that the UK Government's powers are not available merely because they disagree with the policy of the Gender Recognition Reform Bill,” McHarg added.

Senior Tory MP Michael Fabricant has also suggested that the UK Government should let the bill stand or risk compounding support for independence. In response to a lengthy list of nations which already have self-ID laws for trans people in place, Fabricant wrote that opposing the reform could be “an own goal for the Unionists”.

The National: Rosie Duffield MP

However, a group of cross-party MPs – Conservative Miriam Cates, Labour’s Rosie Duffield (above) and the DUP’s Carla Lockhart – have written to the Scottish Secretary asking him to intervene to block the gender reform.

In a letter reported by the Telegraph, the three claim the GRR bill will “threaten the legal basis on which women and girls are currently protected in the rest of the United Kingdom”, as well as posing “a real risk to the safety of women and girls in Scotland”.

This first claim has been dismissed by the Scottish Government, who insist the “bill as passed is within legislative competence”. And the second has been contradicted by Victor Madrigal-Borloz, a UN expert on protection against violence and discrimination based on sexual orientation and gender identity.

He said that the accumulated experience from other countries and regions that have self-ID as the standard – home to some 350 million people – does not support any concerns about abuse of the system by predatory males.

READ MORE: SNP MSP accuses Tory of flouting Holyrood rules to film 'flasher' GRR protest

If the UK Government does look to invoke Section 35 and block the bill – which it must do before January 19 – it will almost certainly face a legal battle with its Scottish counterpart.

A Scottish Government spokesperson has said that “any attempt by the UK Government to undermine the democratic decision of the Scottish Parliament will be vigorously contested”.

The bill was passed by the Scottish parliament with support from every political party. Although the majority of Tory MSPs voted against it, key figures such as former leader Jackson Carlaw and health spokesperson Dr Sandesh Gulhane voted to support the bill.

Prime Minister Rishi Sunak is among the Tory ministers who have suggested that the GRR bill could be challenged, something he said was “completely reasonable”.