However, prominent critics such as MP Joanna Cherry and Ash Regan, a former minister who quit to vote against the plans, have continued to speak out against party policy. 

Many more SNP figures are privately dismayed over Ms Sturgeon’s refusal to back down over an issue that opinion polling suggests puts her at odds with an overwhelming majority of the Scottish public. 

Rishi Sunak on Thursday night intervened in the trans rights debate during an interview in TalkTV, saying that “biological sex really matters in women’s spaces”. 

While Ms Sturgeon has previously been vulnerable during the height of her war with Alex Salmond, she maintained control of her party.

Bryson was moved to a men’s cell in Edinburgh’s Saughton jail last week, but only after a huge public outcry and the SNP leadership initially backing the SPS. 

Douglas Ross, the Scottish Tory leader, told First Minister’s Questions at Holyrood that Bryson was cynically “exploiting” the SNP’s policy of allowing people to self-identify their legal gender.

Although the UK Government has blocked her Bill, Mr Ross pointed out that the SNP administration’s official policy already states: “It is the view of the Scottish Government that trans women are women.”

However, Ms Sturgeon repeatedly avoided questions over whether the rapist was male or female, arguing the two rape convictions were more important in determining which prison the 31-year-old is held in.