According to Finn v The British Bung Manufacturing Company Ltd on the facts of this case it can be.
At Para 235 of the Judgment the Tribunal conclude:
“In our judgment, there is a connection between the word “bald” on the one hand and the protected characteristic of sex on the other. Miss Churchhouse [Counsel for the Respondents] was right to submit that women as well as men may be bald. However, as all three members of the Tribunal will vouchsafe, baldness is much more prevalent in men than women. We find it to be inherently related to sex. (In contrast, we accept that baldness affects (predominantly) adult males of all ages so is inherently not a characteristic of age).”
27th May 2022