It is sometimes cited in the press that FWS will or must lead to the lawful exclusion of women of masculine appearance from women's facilities, and that therefore FWS was an own-goal for women.
This is based on 221 of FWS:
Moreover, women living in the male gender could also be excluded under paragraph 28 without this amounting to gender reassignment discrimination. This might be considered proportionate where reasonable objection is taken to their presence, for example, because the gender reassignment process has given them a masculine appearance or attributes to which reasonable objection might be taken in the context of the women-only service being provided.
I believe what is reported profoundly misunderstands what the Justices wrote in that paragraph.
What they are saying is that there may be places where merely having a masculine appearance or attributes will reasonably be objectionable. That might (for instance) be a rape crisis centre or counselling service. It would not necessarily be (and in my opinion would not be) a generally provided women's toilet. Women can cope with women of masculine appearance in a women's toilet. It is not people (women) of masculine appearance in women's toilet that are an issue. It is men, of all appearances, in women's toilet, that is at issue.
The law does not, therefore give "permission" for women of masculine appearance to be excluded from women's toilets. It does give permission for women of masculine appearance to be excluded from (eg) rape crisis centres or counselling services.
That seems to me to be appropriate.