The court in this case tried to avoid it
[58] There is no statutory definition or Guidance as to the meaning of living in one’s acquired gender. Mr Roberts has referred to this as “a matter of some political controversy”. It is not the role of this Court to adjudicate on political controversy.
The court was referred to three cases
Jay v Secretary of State for Justice [2018] EWHC 2620 (Fam), [2019] 1 FLR 811
Jay was married and divorced three times. He had seven children. The third marriage ended when he went to prison for eight years. Jay claimed that he started living as a woman half way through his second marriage and that he carried on living as a woman "as far as possible" while he was in a male prison.
The evidence of "living in their acquired gender" was a deed poll change of name while in prison and then a passport and driving licence in the new name after release from prison.
.
The second case was
AB v Gender Recognition Panel [2024] EWHC 1456 (Fam), [2025] 1 WLR 227
This case was also referred to in FWS at [91]
AB received hormone replacement therapy and testosterone blockers from the age of 17. Although there was a sentence that sounded quite odd "except for a brief period around 2017 when she ceased taking testosterone blockers to retain capacity for sexual activities.". Perhaps AB wanted to become a father?
The evidence provided was, a deed poll change of name, a letter from a doctor confirming a diagnosis of Asperger's syndrome, a passport, bank statements, a Dutch residence card. All in a new name
.
Finally,
Carpenter v Secretary of State for Justice [2015] EWHC 464 (Admin), [2015] 1 WLR 4111
This case was also referred to in FWS at [85]
Carpenter had actually had surgery. This was considered to be "...overwhelming evidence of the existence now or previously of gender dysphoria and of the desire of the applicant to live in the acquired gender until death."
So, men either get their bits chopped off or just do a deed poll and get a new passport.