This -
https://www.telegraph.co.uk/news/2024/03/30/ons-female-employees-disciplinary-object-trans-toilets/
"Women working for the Office for National Statistics face disciplinary action if they object to male-born colleagues using single-sex lavatories and changing rooms, documents leaked to The Sunday Telegraph reveal.
A cache of HR policies, internal communications and posts from the ONS intranet show that the statistics body has been subject to “institutional capture” by trans activists, gender critical campaigners have alleged...
A set of ONS resources on “Gender Identity and Transitioning at Work” includes a manager’s checklist for supporting a transitioning employee with a section headed “use of single-sex facilities”.
It says: “Have you agreed when the employee will start to use single-sex facilities, such as toilets and changing rooms, appropriate to their acquired gender? This will usually be on the first day of transition.”
The document says that “if colleagues object to sharing facilities with employees going through transition, the situation should be dealt with through communication, discussion and education”.
“If colleagues persist with unreasonable objections you may need to manage the situation via grievance or disciplinary procedures.”"
Much more detail including a response from Sex Matters in the article linked above.