Allison Bailey, the barrister and co-founder of LGB Alliance, has apparently had her hearing date pushed back in her case against Stonewall and her Chambers due to delays on the part of Stonewall and her chambers in handing over all the information required by her under disclosure. Stonewall tried to have her case thrown out and failed so that's a positive.
Allison is suing for discrimination based on her claim that they tried to silence her opposition to Stonewall's view that trans women should be legally recognised as women.
https://allisonbailey.co.uk/Bailey claims that after she helped launch LGB Alliance, Stonewall threatened to withdraw Garden Court Chambers’ membership of the Stonewall Diversity Champions scheme, unless her employer took action against her. She states that as a result of this pressure, she suffered numerous detriments, including lost work opportunities.
The Equalities Act 2010 seems to protect people from discrimination on the grounds of gender reassignment. But Schedule 3 Para 28 of Equalities Act 2010 allows discrimination against people who are proposing to or have undergone gender re-assignment i.e. including those with a Gender Recognition Certificate, if it is a proportionate means of achieving a legitimate aim e.g. in relation to matters such as provision of single-sex services.
https://www.legislation.gov.uk/ukpga/2010/15/schedule/3/paragraph/28If a person has obtained a Gender Recognition Certificate and a new birth certificate stating their new legal sex, they would be legally recognised as having a sex that is contrary to their biology. Presumably when it comes to medical treatments that differ based on biological sex the trans person would make sure their doctors knew their actual biological sex regardless of what their post GRC birth certificate said.