This seems to be the nub of the Court of Appeal decision in Smith . Two of the three judges were very careful to point out that if a lesbian complains of sexuality discrimination then she must compare herself with a gay man. She can compare herself with an actual gay man, or if there isn't one, a hypothetical gay man. She has to show that she has been treated in a worse way than him. But it also means that an employer will have to produce evidence that it treats homosexual employees equally badly.
Discrimination has many causes.
A lesbian can suffer verbal abuse at work as a woman and as a lesbian. As well as complaining of harassment by a colleague as a gay man, in Smith Paul Smith complained of discrimination in the managerial treatment of his complaint of sexuality discrimination. In relation to that claim against management, the judges accepted that the comparison should be with a named woman who was not a lesbian. Mazibuko Jara, Josey Abrahams and Jonathan Berger from the South African National Coalition for Gay and Lesbian Equality. However making a reality of outlawing discrimination is a continuing battle and the Coalition is in the forefront of this struggle in South Africa supported by more than 70 gay, lesbian, bisexual and transgendered organisations and thousands of individuals.