The question on gender identity is voluntary (hurrah, will leave blank).
Of course, one of the dopey comments btl says 'is there an option for "yes please"?', which I seem to recall is one of the reasons why organisations were happy to make the move to asking for gender not sex in the first place.
I note that it asks for 'legal' sex, so presumably those with a GRC can answer according to what is on their re-issued birth certificate? (Wondering how Keira Bell should answer, since her bc has her down as a male).
Very disappointed in the way the Sunday Times has spun this. It's not a blow to trans rights it's a "victory for common sense" (in true Daily Mail parlance) so that data can be recorded accurately. If a town needs to know how much maternity or gynaelogical provision to provide, it needs to know how many biological females live in the town.