It is against the law to give (or not give) someone a job because of their colour or 'race', whether they are black or white. This is true with houses and flats too, and other things like letting them join clubs or schools. It's not against the law to refuse someone a job on the grounds of their religion (except in Northern Ireland).

In 1997 there were many legal complaints from people who felt they had been refused a job, or refused promotion, because of their ethnic origin. Most of these were proved and the employer had to pay damages to the people they'd treated wrongly. Compared to ten years ago, people are more likely today to report that they have been discriminated against at work, though there is good evidence that about a third of employers do discriminate and that this has not gone up or down.

There were also similar complaints to do with housing.

Someone with a job on offer is allowed to say they would like to hear from particular groups if they do not already have many working for them. They are not allowed to give them the job if someone else is better. It is against the law to have quotas for a certain percentage of different groups, though this has been tried in the USA with some success. It is called positive action, and is sometimes proposed for other groups who experience discrimination, like women and people with disabilities.

Here is part of a 1998 advert for a government department:

As the representative of Britain overseas, the Diplomatic Service aims to reflect the diversity of British society. Members of minority ethnic groups and disabled people are currently under-represented in the Diplomatic Service. Applications from these groups are therefore particularly welcomed.