Am I right in thinking having a GRC is now totally irrelevant?

i hope you are right

i think passions run so high that they will find a
slightly different situation and take this through the courts again.

but i really hope you are right

I still don't see your argument. The question went all the way up to the Supreme Court, so that it could finally be put to bed. There's not really much anyone can do if they don't like a Supreme Court ruling.

The Supreme Court was asked to decide on the proper interpretation of the 2010 Equality Act, which applies across Britain.
Lord Hodge said the central question was how the words "woman" and "sex" are defined in the legislation.
He told the court: "The unanimous decision of this court is that the terms woman and sex in the Equality Act 2010 refer to a biological woman and biological sex.
"But we counsel against reading this judgement as a triumph of one or more groups in our society at the expense of another, it is not."
He added that the legislation gives transgender people "protection, not only against discrimination through the protected characteristic of gender reassignment, but also against direct discrimination, indirect discrimination and harassment in substance in their acquired gender".

i do not think this is over. i think, and it is only my view and prediction, that there will be cases arguing that exclusion from space is direct discrimination on them.

i apologise for not getting the final piece of the baker story and i stand corrected. however the fact that this case found for one side the the other shows how hard it is legally
to balance claims about protected characteristics where protecting a characteristic of one person means disadvantaging (in their eyes) another person with a different characteristic.

i have no strong views bar that i do not think this is over or the fight it won.

Trans people have protection under the protected characteristic of gender reassignment. That has always been the case, and what the judge was getting at in the judgement.

That doesnt leave the door open on the issue of single sex spaces, the judgement is clear on that point.

Unless i misremember, the Christian bakers won their case at the Supreme Court.

I don't know how you draw any of those conclusions! The whole point of the judgment is that they can be excluded from women's spaces and provisions. That's what the whole thing was about. On what grounds is someone going to challenge that?

Also, not that it's really relevant, but the bakers won that case in the end. They were allowed not to promote a message they disagreed with. Again, I fail to see the relevance.

Disclaimer: I'm not exactly well educated on all of this. Is a grc like a civil partnership, in terms of you're a woman legally but not biologically

No. Judge (and law) very clear. Trans people, with or without a grc have protections - i think this will mean that excluding them from women's spaces because they don't meet the legal definition of a woman will be challenged .

i am sure you will remember the religious couple who refused to bake a cake for a civil partnership and then when sued, claimed their actions were
protected because of religious belief. the court case found in favour of the couple requesting the service. sometimes legally protected rights conflict.

this is a complex area and i think is going to take some time to get through the detail of what this means

Yes, I've just seen them.

https://www.mumsnet.com/talk/womens_rights/5316077-is-the-concept-of-legal-sex-dead-and-burried

https://www.mumsnet.com/talk/womens_rights/5316079-what-does-this-mean-for-the-gender-recognition-act

"Is the concept of legal sex dead and buried"
And
"What does this mean for the Gender Recognition Act"

Yes, there are a couple especially about this

But are the other threads specifically discussing GRCs?

It hadn't occurred to me about the usefulness of GRCs - perhaps they 'prove' someone is transgender and therefore eligible for protection under the transgender characteristic of the Equality Act? Although if that covers the act of 'transitioning' and not just 'having transitioned' then yes, what is the benefit of a GRC now?

There are a few threads on this topic already, FYI :-)