Hm, that doesn't accord with what KPSS' info is, which I'm sure is correct:
'A male who identifies as ‘transgender’ but who does not have a GRC is initially allocated to a men’s prison. If he wishes to stay there he remains there and decisions will be made about how to manage him in the male estate.
He is entitled to apply to be transferred to a women’s prison. He must provide evidence of ‘living as a woman’. His offending history, past behaviour and anatomy are also considered. The application goes before a Transgender Case Board where a decision will be made. Male prisoners without a GRC are risk assessed in the same way as all male prisoners.
When considering such cases, the Policy Framework states:
The management of individuals who are transgender… must seek to protect both the welfare and rights of the [transgender] individual and the welfare and rights of others in custody around them. These two risks must be considered fully and balanced against each other.
This paragraph is concerning. All male prisoners have the right to be safe in prison. But so do women. There are very good reasons why women in prison require a single-sex environment and why female offenders are entitled to single-sex services that exclude all male prisoners, including those with a transgender identity. The Equality Act, through the single-sex exceptions, contains provision to enable this. We do not believe that the safety, dignity and privacy of female prisoners should be ‘balanced’ against the desire of some males to be housed with them.'
kpssinfo.org/are-male-prisoners-really-in-womens-prisons/