Well, I feel naive. Perhaps everyone already knew this except me, but I've only just learned (in the course of a discussion elsewhere on the net) that there is still a legal obligation on trans people in England and Wales to disclose their "gender history" to a potential marriage partner. This was instituted in the 1973 Matrimonial Causes Act, but rather than being superseded by the 2004 Gender Recognition Act, which purported to recognize transitioned people as their "acquired" gender for legal purposes, that Act reaffirmed the obligation. If disclosure is not made, the non-trans partner can seek to have the marriage annulled.
I was also directed to this recent article on the subject, which I think makes an excellent case as to why this is wrong, inconsistent and probably illegal under European law, but I'm actually shocked that it's the case at all.
Is this news to anyone else?