A police service which employs disproportionately low numbers of people from an ethnic minority background identifies a number of candidates who are as qualified as each other for recruitment to a post, including a candidate from an under-represented ethnic minority background. It would not be unlawful to give preferential treatment to that candidate, provided the comparative merits of other candidates were also taken into consideration.
An employer offers a job to a woman on the basis that women are under-represented in the company’s workforce when there was a male candidate who was more qualified. This would be unlawful direct discrimination.