(1) For the purposes of this Act discrimination shall be taken to occur -

(a) where a person is treated less favourably than another person is, has been or would be treated in a comparable situation on any of the grounds specified in subsection (2) or, if appropriate, subsection (3B) (in this Act referred to as the 'discriminatory grounds') which -

(i) exists,

(ii) existed but no longer exists,

(iii) may exist in the future, or

(iv) is imputed to the person concerned,

(b) where a person who is associated with another person -