This is what I've sent to LAs if anyone wanted wording:
Good Morning
I am writing to express concern that 'sex' has been replaced by 'gender' on your list of protected characteristics. It would appear that either you are conflating sex and gender as the same thing, or that you do not think that biological sex is a cause for discrimination, which it is.
Gender refers to external social markers such as how one acts, looks, dresses, presents. It is a source of discrimination and it is good for it to be protected.
However, sex should be protected as a distinct characteristic. Sex is your biology, your body, your genitals, your hormones. If Sex is not protected then women's reproductive rights are not protected, nor is discrimination against women for pregnancy, or for being physically weaker etc.
Sex and gender are not the same. A person can have female sex biology and present as male gender, and have male sex biology and present as female. It is incredibly important for female equality to retain sex as protected.
Please reconsider this and reinstate sex as a separate protected characteristic, in order to comply with the Equality Act 2010 which retains sex as a category in order to protect females.