I've sat here quietly reading thread as it's unfolded and feel that this point has not very simply and very clearly been made:
This is about way way more than 'just' the GG issue; it's about the fatally flawed entire self-IDing issue.
I feel no threat from a genuine transwoman using the female only changing facility with me, none. I appreciate others may not share that view but that's mine.
However... I feel MASSIVELY fucking threatened by the flimsiness of self-ID'ing and the de facto (& patently clear and real) risk of predatory males now having legit access to my previously safe space via simply self-IDing.
By their nature, male sexual predators who seek female victims target places and organisations where they have access to girls and women (ie as per the heinous history of 'priests' who wanted to target boys pursuing a religious vocation as it gave them both that access as well as simultaneously an automatic cloak of respectability).
You do not have to be a genius to instantly see that it is/will be only a matter of time before a girl or woman is sexually assaulted by a man who has gained access to what was previously a SAFE FUCKING PLACE simply by dint of claiming he ID's as a she.
You can tinkle away and claim that my asserting this obvious fact makes me transphobic but that is clearly bollocks and the weakest of strawman arguements.
So I'm left with wanting to support the genuine tranwoman (let's call her Ellie) who wants to use the changing room, and also wanting to maintain safe spaces for girls and women and, regrettably, there is an inherent clash between those two desires as only a blind person would claim there will not/never will be predatory males utilising the very same self ID'ing as Ellie but for very fucking different reasons.
Ergo it then becomes a question of whose rights matter more? Ellie's right to access those spaces - at the price of opening up female only safe spaces to those with ill intent - OR every biologically born woman and girls right to maintain their safe spaces?
I don't know the stats but relatively speaking Ellie et al (IE genuine transwomen) are a tiny number compared to the c.25-30 million females in this country so it's patently clear which right should triumph in that clash. My problem is what seems to be happening is that the needs and wants of the minority % are - seemingly even without challenge (or, worse in terms of seeking decent outcomes for everyone, any challenge automatically and lazily being mis-labelled as 'transphobic') - sweeping away the rights of the many.
How is this not blindingly obvious to everyone?? 

