This page says why they say "trans":
www.equalityhumanrights.com/en/advice-and-guidance/separate-and-single-sex-service-providers-guide-equality-act-sex-and-gender
"We have used plain English to help explain legal terms. This does not change the meaning of the law.
The Act uses the term ‘transsexual’ for individuals who have the protected characteristic of gender reassignment. We recognise that some people consider this term outdated, so in this guidance we use the term ‘trans’ to refer to a person who has the protected characteristic of gender reassignment.
We use the term ‘biological sex’ because this is how legal sex is defined under the Equality Act for people who do not have a Gender Recognition Certificate."
(Note the "biological sex" part here is already being taken out of context in various TRA Twitter versions. Might be the next urban myth floating about)
And here is the big list of types of single sex services:
www.equalityhumanrights.com/en/advice-and-guidance/when-you-can-provide-separate-or-single-sex-service
From that link, is this one about how to lawfully run a single sex service:
www.equalityhumanrights.com/en/advice-and-guidance/gender-reassignment-provisions-equality-act
"(Schedule 3, para. 28)
If you have met the conditions set out above and have established a separate or single-sex service, you should consider your approach to trans people’s use of the service. In considering your approach and when taking decisions you must meet the conditions set out under the gender reassignment provisions.
Under these provisions, your approach must be a proportionate means of achieving a legitimate aim. This will depend upon the nature of the service and may link to the reason the separate or single-sex service is needed. For example, a legitimate aim could be the privacy and dignity of others. You must then show that your action is a proportionate way to achieve that aim. This requires that you balance the impact upon all service users.
Example: A group counselling session is provided for female victims of sexual assault. The organisers do not allow trans women to attend as they judge that the clients who attend the group session are likely to be traumatised by the presence of a person who is biologically male."
That link also covers the HSE and toilets, which was in the Sex Matters technical consultation response? And in the govt response?
I think this is pretty good but also solidly within what the law says.
No response from SW and co. Mostly they're focused on the conference - I think urging sponsors to pull out. Also busy adding in "non-binary" to things about the conference as well as to tweets about conversion therapy. Basically more shifting of language and morphing of aims.