Sex Matters is a controversial charity that campaigns for the importance of recognising biological sex (as opposed to gender) in law, policy and language. The organisation does not recognise transgender identities.
What do they want to achieve?
Sex Matters recognises two sexes: female and male. The organisation wants to “promote clarity about sex in law, policy and language in order to protect everybody’s rights”.
Full revelations at https://www.standard.co.uk/news/uk/sex-matters-who-hampstead-heath-women-only-pond-b1238022.html