Many thanks for answering @theilltemperedclavecinist I appreciate that you bothered. I feel muddled about this law.
Some points to add in light of what you said -
Only relevant for applying law that is affected by sex, like discrimination law. Doesn't actually change the person's sex for other purposes, such as whether their presence disadvantages a woman or member of a religious minority.
Given
Section 9 of the 2004 Act provides that unless exceptions apply, the effect of a full GRC is that “for all purposes” the person’s sex becomes as certified. As a matter of general principle, a full GRC has the effect of changing the sex that a person has as a protected characteristic for the purposes of the 2010 Act
(GOV.UK)
It is very poor English/law writing in my opinion to be saying “sex for all purposes……. but not for all purposes” ( effectively).
You are allowed but they don't have to answer. I expect the NHS to be able to work out people's sex though (transsexuals have been using it for years).
I would agree, though a doctor was on these threads once saying it can be surprising difficult to make assumptions about people’s sex during the general Pell Mel.
Maybe the NHS would not have a problem, but there can be odd thinking about this, that you would not think possible, as in the response to 2021 petition against the police recording of male crimes as being women’s.
I kid you not:
Officials have noted that ‘biological sex’ has not been defined in the petition. If ‘biological sex’ is defined in terms of anatomy, or chromosomes, then there would be both ethical and logistical challenges for the police or the HMPPS in determining this for every arrested suspect or prisoner. For instance, it would not be appropriate for the police or HMPPS to physically examine every suspect/prisoner in order to determine ‘biological sex’ if it had one of these meanings. Accordingly, there are no plans for the police or HMPPS to record the biological sex of prisoners.*
https://petition.parliament.uk/petitions/590123