Who would agree with this compromise?

I don't think unrecord sex. I'd be happy with adding gender as an additional field on passports etc if people feel uncomfortable just being recorded under their sex.
Free text field so people can put whatever they want or leave it blank, like when religion is recorded. After all being transgender is nothing to be embarrassed about. In some ways it should be recorded, for example for medical statistics, crime statistics, getting the correct medical care, and to make sure trans people are not discriminated against.

Agree clarity is vital.

Spaces might be segregated by sex or gender, but it has to be completely clear which is being used

I do think this is important. Women need to know if the are entering a sex segregated space or one that segregated by gender.

No.

Although I applaud the intent, and have been through similar thought processes.

Ultimately, the classifications of female and male, woman and man, girl and boy, must always relate to sex, and only to sex.

The conflation and confusion has to stop, completely.

Gender is a belief system, like religion, and as such you can legislate to ensure people aren't discriminated against for holding a belief. But there should be no endorsement of that belief on documents, or reallocation of sex based spaces to religion.
And no conflation of sex terms in any recognition of gender.

If a practising Hindu called themselves an orthodox Jew and expected to have synagogues adapt to their Hindu beliefs because they erroneously are calling them Judaism, the law would allow for that false claim to be refuted.

The law must similarly provide for the female sex to refute any misuse of the word female from a person who is not female, even if they claim the word can be applied under their gender beliefs. It cannot.

I wholeheartedly agree with divorcing sex and gender irrevocably.

But I don't think it's tenable any longer to allow a mythical ideology to misappropriate sex based terminology.

Gender can have femininity and masculinity perhaps. But not female, girl or woman. Those terms are sex based and that's that.

Driving licences and passports are legal identification documents.
Say a man ticks the "female" box on the form and presents his woman passport when challenged - then what?

There is precedent for people who have gained a benefit under a law that is repealed, to retain that benefit even though it is no longer possible to grant it under the new law.

Yes GRA is a bad law, created to allow a legal fiction that is no longer necessary. Government should never mandate belief.

I am not talking about anyone in particular but I expect there will be such cases. So how do you handle that if you change a law retrospectively

There are usually grand-fathering clauses, as they're known.

What about the transsexual woman who got a birth certificate changed in 2005 and then married a man legally and they are still married 13 years later. How would your compromise work for them?

I am not talking about anyone in particular but I expect there will be such cases. So how do you handle that if you change a law retrospectively?

Declare their marriage illegal? Or tell the man he has to now become gay and remarry under a same sex relationship?

Get rid of the GRA/GRC altogether. You can't change your sex.

I may have pointed out that this was a discussion point that might usefully have been included within the recent consultation.