I hope that Posie is able to talk to the ordinary person on the sofa and explain to them the reasons why we need to define women. Otherwise anyone falling under the Stonewall definition of transgender: transgender, transsexual, gender-queer (GQ), gender-fluid, non-binary, gender-variant, crossdresser, genderless, agender, nongender, third gender, two-spirit, bi-gender, trans man, trans woman, trans masculine, trans feminine and neutrois. will be able to self ID as female. And that the safeguarding we are expect will be compromised.
And that some women, including those from conservative religious groups, and typically body-insecure teenage girls, will then feel unable to access things: girl guides, crisis centres, sports teams. I would bet on a prediction that the GG will have more applications from transwomen, perhaps from the outer reaches of the Stonewall definition, wanting to be Guide leaders, than they will have from poster transgirls. And that overall they will lose members and volunteers.
I have talked about this to a few female, educated and normally aware, friends and they had no idea of the implications. And were shocked. Education is the key. We then dont need debate as we can rely on ordinary people's common sense.