The Equality Act and gender diversity
The Equality Act prohibits discrimination based on gender identity and gender expression.
Human gender identity and gender expression come in a multitude of forms, and not everyone is unambiguously female or male. How people perceive their gender can be seen as a grade on a scale. People may identify as male or female, or something in between. Some do not identify as being part of the traditional classification of male or female at all. That is why verbal expressions and classification do not easily fit in with real life. On an individual level the classification mainly depends on how each person perceives their gender.
Publication: The Equality Act, discrimination and gender diversity (STM, 2016)