That's why nobody noticed or cared when the Gender Recognition Act was passed in 2004 - there were no evangelical GC feminists opposing it, or if there was they didn't have a platform like they do now.
That's because back then, there wasn't a really a widely held conception of "GC feminists". It would have been an oxymoron - of course feminists were critical of gender roles/stereotypes.
On feminist boards there was discussion about why "transsexuals" presented themselves in a highly feminised manner. It was explained by transsexuals that doing so eased their dismorphia around their primary sexual characteristics.
Feminists were widely sympathetic as "transsexuals" were predominantly presented as individuals sexualy attracted to the male sex who had or were planning to have surgery to remove their penis.
I was horrified that these individuals may be sent to the male prison estate. But I made an error, I assumed that if out of a very small cohort of 5k (which was the estimated proportion of trans people who would be eligible for this certificate) would go to prison for crimes similar to the type of crimes females committed.
It never occurred to me that they might be rapists. That the category of people known as transsexuals would become "transwomen" which would gradually expand to include individuals who did not want body modification or who had sexual inclinations for doing so.
Back then there were minority views against the change to birth certificate as it is a document stating a fact. However it was perceived that the document was required to get passport/drivers license changed.
There were a few who rejected the concept of calling male transsexuals women as a courtesy. They argued that it wouldn't be enough. That the word female would be coopted. That women would be hampered when discussing the reality of their lives relating to biology and sexism. That lesbians would no longer be able to define as being attracted to the female body.
Frankly, we thought they were a bit paranoid. After all the transsexuals debating with us were all very empathic and insistent on understanding how it would be normal for a female to share an intimate space. (Notice cis hadn't come in then and when it did it referred to biology)
It really pisses me off that those lone voices were correct.
I've watched the narrative change - from "I feel like I'm in the wrong body I need to change it" to "I'm in the wrong body I need to change it" to "I don't need to change my body but it's actually female because I feel female and so is my penis"
That's why there is the push back. Personally it's not mumsnet that has changed my mind it is reading the blogs of tras. Seeing the abuse that old school transsexuals receive. The hatred and misogyny (fish lips anyone) from people who claim to be transwoman or allies. I say claim because a lot of the narrative is the same as the mras who I was butting heads with 10 years ago.
Mumsnet has become a focus because this debate is being closed down elsewhere. I believe it is actually TRA who driving the increase in traffic here. When your average person grasps that despite being in favour of self ID they are considered transphobic because they don't actually believe that transwoman are adult human females.
I'm seeing it on my own timeline, a very vulnerable individual (nb) stating transwoman are women, defriend me if you disagree. Friends are trying to delicately disagree, people who had no real opinion are starting to say hang on a minute "eg x spent years campaigning against s. 28 but is suddenly a bigot because x won't repeat the mantra."