A person's race is a protected characteristic under the Equality Act 2010. The term "race" is defined in Section 9(1) as including a person's colour, nationality, or ethnic/national origins. However, Section 9(5) contains an unusual provision (my emphasis in bold):
A Minister of the Crown
(a) must by order amend this section so as to provide for caste to be an aspect of race;
(b) may by order amend this Act so as to provide for an exception to a provision of this Act to apply, or not to apply, to caste or to apply, or not to apply, to caste in specified circumstances.
This appears to suggest that the definition of race was incomplete, raising the question of why "caste" wasn't simply included in Section 9(1) to begin with. On the surface, it seems strange for the act to simultaneously expressly exclude caste from the definition of race, and also note that a minister must amend the definition.
Is there a reason why the act was drafted in this way?